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    Command:

    csh

    
    
    

    SYNOPSIS

           tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
           tcsh -l
    
    
    

    DESCRIPTION

           tcsh  is  an enhanced but completely compatible version of the Berkeley
           UNIX C shell, csh(1).  It is a command language interpreter usable both
           as an interactive login shell and a shell script command processor.  It
           includes a command-line editor  (see  The  command-line  editor),  pro-
           grammable  word  completion (see Completion and listing), spelling cor-
           rection (see Spelling correction), a  history  mechanism  (see  History
           substitution),  job  control  (see  Jobs) and a C-like syntax.  The NEW
           FEATURES section describes major  enhancements  of  tcsh  over  csh(1).
           Throughout  this  manual,  features  of  tcsh  not found in most csh(1)
           implementations (specifically, the 4.4BSD csh) are labeled with  '(+)',
           and features which are present in csh(1) but not usually documented are
           labeled with '(u)'.
    
       Argument list processing
           If the first argument (argument 0) to the shell is '-'  then  it  is  a
           login shell.  A login shell can be also specified by invoking the shell
           with the -l flag as the only argument.
    
           The rest of the flag arguments are interpreted as follows:
    
           -b  Forces a ''break'' from  option  processing,  causing  any  further
               shell arguments to be treated as non-option arguments.  The remain-
               ing arguments will not be interpreted as shell options.   This  may
               be used to pass options to a shell script without confusion or pos-
               sible subterfuge.  The shell will not  run  a  set-user  ID  script
               without this option.
    
           -c  Commands  are  read  from  the  following  argument  (which must be
               present, and must be a single  argument),  stored  in  the  command
               shell  variable  for  reference, and executed.  Any remaining argu-
               ments are placed in the argv shell variable.
    
           -d  The shell loads the directory stack from  ~/.cshdirs  as  described
               under Startup and shutdown, whether or not it is a login shell. (+)
    
           -Dname[=value]
               Sets the environment variable name to value. (Domain/OS only) (+)
    
           -e  The shell exits if any invoked  command  terminates  abnormally  or
               yields a non-zero exit status.
    
           -f  The  shell  does not load any resource or startup files, or perform
               any command hashing, and thus starts faster.
    
           -F  The shell uses fork(2) instead of vfork(2) to spawn processes. (+)
    
           -i  The shell is interactive and prompts for its top-level input,  even
    
           -s  Command input is taken from the standard input.
    
           -t  The shell reads and executes a single line of input.  A '\' may  be
               used  to  escape  the  newline at the end of this line and continue
               onto another line.
    
           -v  Sets the verbose shell variable, so that command  input  is  echoed
               after history substitution.
    
           -x  Sets  the  echo shell variable, so that commands are echoed immedi-
               ately before execution.
    
           -V  Sets the verbose shell variable even before executing ~/.tcshrc.
    
           -X  Is to -x as -V is to -v.
    
           --help
               Print a help message on the standard output and exit. (+)
    
           --version
               Print the version/platform/compilation options on the standard out-
               put  and  exit.   This information is also contained in the version
               shell variable. (+)
    
           After processing of flag arguments, if arguments remain but none of the
           -c,  -i,  -s,  or -t options were given, the first argument is taken as
           the name of a file of commands, or ''script'',  to  be  executed.   The
           shell opens this file and saves its name for possible resubstitution by
           '$0'.  Because many systems use either the standard version 6  or  ver-
           sion  7  shells whose shell scripts are not compatible with this shell,
           the shell uses such a 'standard' shell to execute a script whose  first
           character is not a '#', i.e., that does not start with a comment.
    
           Remaining arguments are placed in the argv shell variable.
    
       Startup and shutdown
           A  login  shell  begins  by  executing  commands  from the system files
           /etc/csh.cshrc and /etc/csh.login.   It  then  executes  commands  from
           files  in  the  user's  home  directory:  first  ~/.tcshrc  (+)  or, if
           ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or the value of  the
           histfile shell variable), then ~/.login, and finally ~/.cshdirs (or the
           value of  the  dirsfile  shell  variable)  (+).   The  shell  may  read
           /etc/csh.login  before  instead  of  after /etc/csh.cshrc, and ~/.login
           before instead of after ~/.tcshrc or ~/.cshrc  and  ~/.history,  if  so
           compiled; see the version shell variable. (+)
    
           Non-login  shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on
           startup.
    
           For examples of startup  files,  please  consult  http://tcshrc.source-
           forge.net.
           words, places it on the command history list, parses  it  and  executes
           each command in the line.
    
           One can log out by typing '^D' on an empty line, 'logout' or 'login' or
           via the shell's autologout mechanism (see the  autologout  shell  vari-
           able).  When a login shell terminates it sets the logout shell variable
           to 'normal' or 'automatic' as appropriate, then executes commands  from
           the  files  /etc/csh.logout  and  ~/.logout.  The shell may drop DTR on
           logout if so compiled; see the version shell variable.
    
           The names of the system login and logout files vary from system to sys-
           tem for compatibility with different csh(1) variants; see FILES.
    
       Editing
           We  first describe The command-line editor.  The Completion and listing
           and Spelling correction sections describe  two  sets  of  functionality
           that  are  implemented  as  editor commands but which deserve their own
           treatment.  Finally, Editor commands lists  and  describes  the  editor
           commands specific to the shell and their default bindings.
    
       The command-line editor (+)
           Command-line  input  can  be edited using key sequences much like those
           used in GNU Emacs or vi(1).  The editor is active only  when  the  edit
           shell  variable  is  set, which it is by default in interactive shells.
           The bindkey builtin can display and change key  bindings.   Emacs-style
           key  bindings are used by default (unless the shell was compiled other-
           wise; see the version shell variable), but bindkey can change  the  key
           bindings to vi-style bindings en masse.
    
           The  shell always binds the arrow keys (as defined in the TERMCAP envi-
           ronment variable) to
    
               down    down-history
               up      up-history
               left    backward-char
               right   forward-char
    
           unless doing so would alter another single-character binding.  One  can
           set  the  arrow  key escape sequences to the empty string with settc to
           prevent these bindings.  The ANSI/VT100 sequences for  arrow  keys  are
           always bound.
    
           Other  key  bindings are, for the most part, what Emacs and vi(1) users
           would expect and can easily be displayed by bindkey,  so  there  is  no
           need to list them here.  Likewise, bindkey can list the editor commands
           with a short description of each.
    
           Note that editor commands do not have the same notion of a ''word''  as
           does  the  shell.   The editor delimits words with any non-alphanumeric
           characters not in the shell variable wordchars, while the shell  recog-
           nizes  only whitespace and some of the characters with special meanings
           to it, listed under Lexical structure.
           '/' or space is added to the end if it isn't already there.
    
           Completion works anywhere in the line, not at just the  end;  completed
           text  pushes the rest of the line to the right.  Completion in the mid-
           dle of a word often results in leftover characters to the right of  the
           cursor that need to be deleted.
    
           Commands  and  variables  can  be  completed in much the same way.  For
           example, typing 'em[tab]' would complete 'em' to 'emacs' if emacs  were
           the  only  command  on your system beginning with 'em'.  Completion can
           find a command in any directory in path or if given  a  full  pathname.
           Typing  'echo  $ar[tab]'  would  complete  '$ar' to '$argv' if no other
           variable began with 'ar'.
    
           The shell parses the input buffer to determine  whether  the  word  you
           want  to  complete  should be completed as a filename, command or vari-
           able.  The first word in the buffer and the first word  following  ';',
           '|',  '|&',  '&&' or '||' is considered to be a command.  A word begin-
           ning with '$' is considered to be a variable.  Anything else is a file-
           name.  An empty line is 'completed' as a filename.
    
           You  can  list the possible completions of a word at any time by typing
           '^D' to run the delete-char-or-list-or-eof editor command.   The  shell
           lists  the  possible  completions  using  the  ls-F builtin (q.v.)  and
           reprints the prompt and unfinished command line, for example:
    
               > ls /usr/l[^D]
               lbin/       lib/        local/      lost+found/
               > ls /usr/l
    
           If the autolist shell variable is set, the shell  lists  the  remaining
           choices (if any) whenever completion fails:
    
               > set autolist
               > nm /usr/lib/libt[tab]
               libtermcap.a@ libtermlib.a@
               > nm /usr/lib/libterm
    
           If autolist is set to 'ambiguous', choices are listed only when comple-
           tion fails and adds no new characters to the word being completed.
    
           A filename to be completed can contain variables, your own  or  others'
           home  directories  abbreviated with '~' (see Filename substitution) and
           directory stack entries abbreviated with '=' (see Directory stack  sub-
           stitution).  For example,
    
               > ls ~k[^D]
               kahn    kas     kellogg
               > ls ~ke[tab]
               > ls ~kellogg/
    
           or
           sibilities anywhere on a line, and list-choices  (or  any  one  of  the
           related  editor  commands that do or don't delete, list and/or log out,
           listed under delete-char-or-list-or-eof) can be bound to '^D' with  the
           bindkey builtin command if so desired.
    
           The complete-word-fwd and complete-word-back editor commands (not bound
           to any keys by default) can be used to cycle up and  down  through  the
           list  of possible completions, replacing the current word with the next
           or previous word in the list.
    
           The shell variable fignore can be set to  a  list  of  suffixes  to  be
           ignored by completion.  Consider the following:
    
               > ls
               Makefile        condiments.h~   main.o          side.c
               README          main.c          meal            side.o
               condiments.h    main.c~
               > set fignore = (.o \~)
               > emacs ma[^D]
               main.c   main.c~  main.o
               > emacs ma[tab]
               > emacs main.c
    
           'main.c~'  and  'main.o'  are  ignored by completion (but not listing),
           because they end in suffixes in fignore.  Note that a '\' was needed in
           front  of  '~'  to  prevent it from being expanded to home as described
           under Filename substitution.  fignore is ignored if only one completion
           is possible.
    
           If  the  complete  shell  variable  is  set to 'enhance', completion 1)
           ignores case and 2) considers periods, hyphens  and  underscores  ('.',
           '-'  and  '_')  to be word separators and hyphens and underscores to be
           equivalent.  If you had the following files
    
               comp.lang.c      comp.lang.perl   comp.std.c++
               comp.lang.c++    comp.std.c
    
           and typed 'mail -f c.l.c[tab]', it  would  be  completed  to  'mail  -f
           comp.lang.c',  and  ^D  would  list  'comp.lang.c' and 'comp.lang.c++'.
           'mail -f c..c++[^D]' would  list  'comp.lang.c++'  and  'comp.std.c++'.
           Typing 'rm a--file[^D]' in the following directory
    
               A_silly_file    a-hyphenated-file    another_silly_file
    
           would  list  all  three  files, because case is ignored and hyphens and
           underscores are equivalent.  Periods, however, are  not  equivalent  to
           hyphens or underscores.
    
           Completion  and  listing are affected by several other shell variables:
           recexact can be set to complete on the shortest possible unique  match,
           even if more typing might result in a longer match:
    
           rect  the  word  to  be completed (see Spelling correction) before each
           completion attempt and correct can be set to complete commands automat-
           ically  after  one hits 'return'.  matchbeep can be set to make comple-
           tion beep or not beep in a variety of situations, and nobeep can be set
           to  never  beep  at  all.   nostat  can be set to a list of directories
           and/or patterns that match directories to prevent the completion mecha-
           nism from stat(2)ing those directories.  listmax and listmaxrows can be
           set to limit the number of  items  and  rows  (respectively)  that  are
           listed  without asking first.  recognize_only_executables can be set to
           make the shell list only executables when listing commands, but  it  is
           quite slow.
    
           Finally, the complete builtin command can be used to tell the shell how
           to complete words other than filenames, commands and  variables.   Com-
           pletion  and listing do not work on glob-patterns (see Filename substi-
           tution), but the list-glob  and  expand-glob  editor  commands  perform
           equivalent functions for glob-patterns.
    
       Spelling correction (+)
           The shell can sometimes correct the spelling of filenames, commands and
           variable names as well as completing and listing them.
    
           Individual words can be spelling-corrected with the  spell-word  editor
           command (usually bound to M-s and M-S) and the entire input buffer with
           spell-line (usually bound to M-$).  The correct shell variable  can  be
           set to 'cmd' to correct the command name or 'all' to correct the entire
           line each time return is typed, and autocorrect can be set  to  correct
           the word to be completed before each completion attempt.
    
           When  spelling correction is invoked in any of these ways and the shell
           thinks that any part of the command line is misspelled, it prompts with
           the corrected line:
    
               > set correct = cmd
               > lz /usr/bin
               CORRECT>ls /usr/bin (y|n|e|a)?
    
           One can answer 'y' or space to execute the corrected line, 'e' to leave
           the uncorrected command in the input buffer, 'a' to abort  the  command
           as if '^C' had been hit, and anything else to execute the original line
           unchanged.
    
           Spelling correction recognizes user-defined completions (see  the  com-
           plete  builtin  command).   If  an input word in a position for which a
           completion is defined resembles a word in the completion list, spelling
           correction  registers  a  misspelling and suggests the latter word as a
           correction.  However, if the input word does not match any of the  pos-
           sible  completions for that position, spelling correction does not reg-
           ister a misspelling.
    
           Like completion, spelling correction works anywhere in the line,  push-
           ing  the rest of the line to the right and possibly leaving extra char-
           'M-character'  a meta character, typed as escape-character on terminals
           without a meta key.  Case counts, but commands that are bound  to  let-
           ters by default are bound to both lower- and uppercase letters for con-
           venience.
    
           complete-word (tab)
                   Completes a word as described under Completion and listing.
    
           complete-word-back (not bound)
                   Like complete-word-fwd, but steps up from the end of the  list.
    
           complete-word-fwd (not bound)
                   Replaces  the  current  word with the first word in the list of
                   possible completions.  May be repeated to step down through the
                   list.   At the end of the list, beeps and reverts to the incom-
                   plete word.
    
           complete-word-raw (^X-tab)
                   Like complete-word, but ignores user-defined completions.
    
           copy-prev-word (M-^_)
                   Copies the previous word in the current  line  into  the  input
                   buffer.  See also insert-last-word.
    
           dabbrev-expand (M-/)
                   Expands  the  current word to the most recent preceding one for
                   which the current is a leading substring, wrapping  around  the
                   history  list  (once)  if  necessary.  Repeating dabbrev-expand
                   without any intervening typing changes  to  the  next  previous
                   word etc., skipping identical matches much like history-search-
                   backward does.
    
           delete-char (not bound)
                   Deletes the character under the cursor.  See also  delete-char-
                   or-list-or-eof.
    
           delete-char-or-eof (not bound)
                   Does  delete-char  if  there is a character under the cursor or
                   end-of-file on an empty line.  See also delete-char-or-list-or-
                   eof.
    
           delete-char-or-list (not bound)
                   Does  delete-char  if  there is a character under the cursor or
                   list-choices at the end of the line.  See also  delete-char-or-
                   list-or-eof.
    
           delete-char-or-list-or-eof (^D)
                   Does  delete-char  if  there  is  a character under the cursor,
                   list-choices at the end of the line or end-of-file on an  empty
                   line.  See also those three commands, each of which does only a
                   single action, and delete-char-or-eof, delete-char-or-list  and
                   list-or-eof,  each  of  which  does  a different two out of the
                   the autoexpand shell variable.
    
           expand-glob (^X-*)
                   Expands  the glob-pattern to the left of the cursor.  See File-
                   name substitution.
    
           expand-line (not bound)
                   Like expand-history, but expands history substitutions in  each
                   word in the input buffer,
    
           expand-variables (^X-$)
                   Expands  the  variable to the left of the cursor.  See Variable
                   substitution.
    
           history-search-backward (M-p, M-P)
                   Searches backwards through  the  history  list  for  a  command
                   beginning  with  the current contents of the input buffer up to
                   the cursor and copies it into the  input  buffer.   The  search
                   string  may  be a glob-pattern (see Filename substitution) con-
                   taining '*', '?', '[]' or '{}'.   up-history  and  down-history
                   will  proceed  from  the appropriate point in the history list.
                   Emacs mode only.  See also history-search-forward and i-search-
                   back.
    
           history-search-forward (M-n, M-N)
                   Like history-search-backward, but searches forward.
    
           i-search-back (not bound)
                   Searches  backward  like  history-search-backward,  copies  the
                   first match into the input buffer with the cursor positioned at
                   the  end of the pattern, and prompts with 'bck: ' and the first
                   match.  Additional  characters  may  be  typed  to  extend  the
                   search,  i-search-back  may be typed to continue searching with
                   the same pattern, wrapping around the history  list  if  neces-
                   sary,  (i-search-back  must  be bound to a single character for
                   this to work) or one of the following special characters may be
                   typed:
    
                       ^W      Appends  the  rest  of the word under the cursor to
                               the search pattern.
                       delete (or any character bound to backward-delete-char)
                               Undoes the effect of the last character  typed  and
                               deletes  a  character  from  the  search pattern if
                               appropriate.
                       ^G      If the previous search was successful,  aborts  the
                               entire  search.  If not, goes back to the last suc-
                               cessful search.
                       escape  Ends the search, leaving the current  line  in  the
                               input buffer.
    
                   Any other character not bound to self-insert-command terminates
                   the search, leaving the current line in the input  buffer,  and
                   choices-raw.
    
           list-choices-raw (^X-^D)
                   Like list-choices, but ignores user-defined completions.
    
           list-glob (^X-g, ^X-G)
                   Lists (via the ls-F builtin) matches to the  glob-pattern  (see
                   Filename substitution) to the left of the cursor.
    
           list-or-eof (not bound)
                   Does  list-choices  or  end-of-file on an empty line.  See also
                   delete-char-or-list-or-eof.
    
           magic-space (not bound)
                   Expands history substitutions in the current line, like expand-
                   history,  and  inserts  a space.  magic-space is designed to be
                   bound to the space bar, but is not bound by default.
    
           normalize-command (^X-?)
                   Searches for the current word in PATH  and,  if  it  is  found,
                   replaces  it  with  the  full  path to the executable.  Special
                   characters are quoted.  Aliases are  expanded  and  quoted  but
                   commands  within  aliases are not.  This command is useful with
                   commands that take commands as arguments, e.g., 'dbx'  and  'sh
                   -x'.
    
           normalize-path (^X-n, ^X-N)
                   Expands  the  current word as described under the 'expand' set-
                   ting of the symlinks shell variable.
    
           overwrite-mode (unbound)
                   Toggles between input and overwrite modes.
    
           run-fg-editor (M-^Z)
                   Saves the current input line and looks for a stopped job with a
                   name  equal  to the last component of the file name part of the
                   EDITOR or VISUAL environment variables, or, if neither is  set,
                   'ed'  or  'vi'.   If such a job is found, it is restarted as if
                   'fg %job' had been typed.  This is  used  to  toggle  back  and
                   forth between an editor and the shell easily.  Some people bind
                   this command to '^Z' so they can do this even more easily.
    
           run-help (M-h, M-H)
                   Searches for documentation on the current  command,  using  the
                   same  notion  of  'current command' as the completion routines,
                   and prints it.  There is no way to use  a  pager;  run-help  is
                   designed  for  short help files.  If the special alias helpcom-
                   mand is defined, it is run with the  command  name  as  a  sole
                   argument.   Else,  documentation should be in a file named com-
                   mand.help, command.1, command.6, command.8  or  command,  which
                   should  be  in one of the directories listed in the HPATH envi-
                   ronment variable.  If there is more than one help file only the
                   creates  two  bindings: the first character to sequence-lead-in
                   and the whole sequence to the command.  All sequences beginning
                   with  a  character  bound  to  sequence-lead-in are effectively
                   bound to undefined-key unless bound to another command.
    
           spell-line (M-$)
                   Attempts to correct the spelling of  each  word  in  the  input
                   buffer,  like spell-word, but ignores words whose first charac-
                   ter is one of '-', '!', '^' or '%', or which contain  '\',  '*'
                   or  '?', to avoid problems with switches, substitutions and the
                   like.  See Spelling correction.
    
           spell-word (M-s, M-S)
                   Attempts to  correct  the  spelling  of  the  current  word  as
                   described  under Spelling correction.  Checks each component of
                   a word which appears to be a pathname.
    
           toggle-literal-history (M-r, M-R)
                   Expands or  'unexpands'  history  substitutions  in  the  input
                   buffer.  See also expand-history and the autoexpand shell vari-
                   able.
    
           undefined-key (any unbound key)
                   Beeps.
    
           up-history (up-arrow, ^P)
                   Copies the previous entry in the history list  into  the  input
                   buffer.  If histlit is set, uses the literal form of the entry.
                   May be repeated to step up through the history  list,  stopping
                   at the top.
    
           vi-search-back (?)
                   Prompts  with '?' for a search string (which may be a glob-pat-
                   tern, as with history-search-backward),  searches  for  it  and
                   copies it into the input buffer.  The bell rings if no match is
                   found.  Hitting return ends the  search  and  leaves  the  last
                   match  in the input buffer.  Hitting escape ends the search and
                   executes the match.  vi mode only.
    
           vi-search-fwd (/)
                   Like vi-search-back, but searches forward.
    
           which-command (M-?)
                   Does a which (see the description of the  builtin  command)  on
                   the first word of the input buffer.
    
           yank-pop (M-y)
                   When  executed  immediately  after  a yank or another yank-pop,
                   replaces the yanked string with the next previous  string  from
                   the  killring.  This  also has the effect of rotating the kill-
                   ring, such  that  this  string  will  be  considered  the  most
                   recently  killed  by  a  later yank command. Repeating yank-pop
    
           preceding  it  with  a backslash ('\') or enclosing it in single ('''),
           double ('"') or backward (''') quotes.  When  not  otherwise  quoted  a
           newline  preceded  by a '\' is equivalent to a blank, but inside quotes
           this sequence results in a newline.
    
           Furthermore, all Substitutions (see below) except History  substitution
           can  be  prevented  by  enclosing  the strings (or parts of strings) in
           which they appear with single quotes or by quoting the crucial  charac-
           ter(s) (e.g., '$' or ''' for Variable substitution or Command substitu-
           tion respectively) with '\'.   (Alias  substitution  is  no  exception:
           quoting  in any way any character of a word for which an alias has been
           defined prevents substitution of the alias.  The usual way  of  quoting
           an  alias  is  to precede it with a backslash.) History substitution is
           prevented by backslashes but not by single quotes.  Strings quoted with
           double  or  backward  quotes  undergo Variable substitution and Command
           substitution, but other substitutions are prevented.
    
           Text inside single or double quotes becomes a single word (or  part  of
           one).   Metacharacters  in these strings, including blanks and tabs, do
           not form separate words.  Only in one special case (see Command substi-
           tution  below)  can a double-quoted string yield parts of more than one
           word; single-quoted strings never do.   Backward  quotes  are  special:
           they  signal Command substitution (q.v.), which may result in more than
           one word.
    
           Quoting complex strings, particularly strings which themselves  contain
           quoting characters, can be confusing.  Remember that quotes need not be
           used as they are in human writing!  It may be easier to  quote  not  an
           entire  string,  but only those parts of the string which need quoting,
           using different types of quoting to do so if appropriate.
    
           The backslash_quote shell variable (q.v.) can  be  set  to  make  back-
           slashes  always  quote  '\',  ''',  and '"'.  (+) This may make complex
           quoting tasks easier, but it can cause syntax errors in csh(1) scripts.
    
       Substitutions
           We  now  describe the various transformations the shell performs on the
           input in the order in which they occur.  We note in  passing  the  data
           structures  involved  and the commands and variables which affect them.
           Remember that substitutions can be prevented by  quoting  as  described
           under Lexical structure.
    
       History substitution
           Each  command,  or  ''event'',  input from the terminal is saved in the
           history list.  The previous command is always saved,  and  the  history
           shell  variable can be set to a number to save that many commands.  The
           histdup shell variable can be set to not save duplicate events or  con-
           secutive duplicate events.
    
           Saved  commands  are  numbered sequentially from 1 and stamped with the
           time.  It is not usually necessary to use event numbers, but  the  cur-
           rent  event  number can be made part of the prompt by placing an '!' in
           the previous command with little typing and a  high  degree  of  confi-
           dence.
    
           History  substitutions  begin  with  the character '!'.  They may begin
           anywhere in the input stream, but they do not nest.   The  '!'  may  be
           preceded  by  a  '\' to prevent its special meaning; for convenience, a
           '!' is passed unchanged when it is followed by a blank,  tab,  newline,
           '=' or '('.  History substitutions also occur when an input line begins
           with '^'.  This special abbreviation  will  be  described  later.   The
           characters  used  to  signal  history substitution ('!' and '^') can be
           changed by setting the histchars shell variable.  Any input line  which
           contains a history substitution is printed before it is executed.
    
           A history substitution may have an ''event specification'', which indi-
           cates the event from which words are to be  taken,  a  ''word  designa-
           tor'',  which  selects particular words from the chosen event, and/or a
           ''modifier'', which manipulates the selected words.
    
           An event specification can be
    
               n       A number, referring to a particular event
               -n      An offset, referring to the  event  n  before  the  current
                       event
               #       The  current  event.   This  should  be  used  carefully in
                       csh(1), where there is no check for recursion.  tcsh allows
                       10 levels of recursion.  (+)
               !       The previous event (equivalent to '-1')
               s       The  most  recent  event  whose  first word begins with the
                       string s
               ?s?     The most recent event which contains  the  string  s.   The
                       second  '?' can be omitted if it is immediately followed by
                       a newline.
    
           For example, consider this bit of someone's history list:
    
                9  8:30    nroff -man wumpus.man
               10  8:31    cp wumpus.man wumpus.man.old
               11  8:36    vi wumpus.man
               12  8:37    diff wumpus.man.old wumpus.man
    
           The commands are shown with their event numbers and time  stamps.   The
           current  event,  which we haven't typed in yet, is event 13.  '!11' and
           '!-2' refer to event 11.  '!!' refers to the previous event, 12.   '!!'
           can  be  abbreviated  '!'  if  it  is followed by ':' (':' is described
           below).  '!n' refers to event 9, which begins with 'n'.  '!?old?'  also
           refers  to event 12, which contains 'old'.  Without word designators or
           modifiers history references simply expand to the entire event,  so  we
           might  type  '!cp'  to redo the copy command or '!!|more' if the 'diff'
           output scrolled off the top of the screen.
    
           History references may be insulated  from  the  surrounding  text  with
           braces  if  necessary.   For  example, '!vdoc' would look for a command
           are:
    
               0       The first (command) word
               n       The nth argument
               ^       The first argument, equivalent to '1'
               $       The last argument
               %       The word matched by an ?s? search
               x-y     A range of words
               -y      Equivalent to '0-y'
               *       Equivalent to '^-$', but returns nothing if the event  con-
                       tains only 1 word
               x*      Equivalent to 'x-$'
               x-      Equivalent to 'x*', but omitting the last word ('$')
    
           Selected  words  are inserted into the command line separated by single
           blanks.  For example, the 'diff' command in the previous example  might
           have been typed as 'diff !!:1.old !!:1' (using ':1' to select the first
           argument from the previous event) or 'diff !-2:2 !-2:1' to  select  and
           swap  the arguments from the 'cp' command.  If we didn't care about the
           order of the 'diff' we might have said 'diff !-2:1-2' or  simply  'diff
           !-2:*'.   The  'cp'  command  might  have  been  written 'cp wumpus.man
           !#:1.old', using '#' to refer to the current event.  '!n:-  hurkle.man'
           would  reuse the first two words from the 'nroff' command to say 'nroff
           -man hurkle.man'.
    
           The ':' separating the event specification from the word designator can
           be omitted if the argument selector begins with a '^', '$', '*', '%' or
           '-'.  For example, our 'diff' command might  have  been  'diff  !!^.old
           !!^'  or, equivalently, 'diff !!$.old !!$'.  However, if '!!' is abbre-
           viated '!', an argument selector beginning with '-' will be interpreted
           as an event specification.
    
           A  history reference may have a word designator but no event specifica-
           tion.  It then references the previous command.  Continuing our  'diff'
           example,  we  could  have  said  simply 'diff !^.old !^' or, to get the
           arguments in the opposite order, just 'diff !*'.
    
           The word or words in a history reference  can  be  edited,  or  ''modi-
           fied'',  by following it with one or more modifiers, each preceded by a
           ':':
    
               h       Remove a trailing pathname component, leaving the head.
               t       Remove all leading pathname components, leaving the tail.
               r       Remove a filename extension '.xxx', leaving the root  name.
               e       Remove all but the extension.
               u       Uppercase the first lowercase letter.
               l       Lowercase the first uppercase letter.
               s/l/r/  Substitute  l  for  r.   l is simply a string like r, not a
                       regular expression as in the eponymous ed(1) command.   Any
                       character  may  be used as the delimiter in place of '/'; a
                       '\' can be used to quote the delimiter expect '(', ')', '|'
                       and  '>'  inside  l  and  r.  The character '&' in the r is
                       tions.
               x       Like  q, but break into words at blanks, tabs and newlines.
    
           Modifiers are applied to only the first modifiable word (unless 'g'  is
           used).  It is an error for no word to be modifiable.
    
           For  example,  the 'diff' command might have been written as 'diff wum-
           pus.man.old !#^:r', using ':r' to remove '.old' from the first argument
           on  the  same  line ('!#^').  We could say 'echo hello out there', then
           'echo !*:u' to capitalize 'hello', 'echo !*:au' to say it out loud,  or
           'echo  !*:agu'  to really shout.  We might follow 'mail -s "I forgot my
           password" rot' with '!:s/rot/root' to correct the  spelling  of  'root'
           (but see Spelling correction for a different approach).
    
           There is a special abbreviation for substitutions.  '^', when it is the
           first character on an input line, is equivalent  to  '!:s^'.   Thus  we
           might have said '^rot^root' to make the spelling correction in the pre-
           vious example.  This is the only history substitution  which  does  not
           explicitly begin with '!'.
    
           (+) In csh as such, only one modifier may be applied to each history or
           variable expansion.  In tcsh, more than one may be used, for example
    
               % mv wumpus.man /usr/man/man1/wumpus.1
               % man !$:t:r
               man wumpus
    
           In csh, the result would be 'wumpus.1:r'.  A substitution followed by a
           colon may need to be insulated from it with braces:
    
               > mv a.out /usr/games/wumpus
               > setenv PATH !$:h:$PATH
               Bad ! modifier: $.
               > setenv PATH !{-2$:h}:$PATH
               setenv PATH /usr/games:/bin:/usr/bin:.
    
           The  first attempt would succeed in csh but fails in tcsh, because tcsh
           expects another modifier after the second colon rather than '$'.
    
           Finally, history can be accessed through the editor as well as  through
           the  substitutions  just described.  The up- and down-history, history-
           search-backward and -forward, i-search-back  and  -fwd,  vi-search-back
           and  -fwd,  copy-prev-word  and insert-last-word editor commands search
           for events in the history list and copy them  into  the  input  buffer.
           The toggle-literal-history editor command switches between the expanded
           and literal forms of history lines in the input buffer.  expand-history
           and expand-line expand history substitutions in the current word and in
           the entire input buffer respectively.
    
       Alias substitution
           The shell maintains a list of aliases  which  can  be  set,  unset  and
           printed  by  the  alias  and unalias commands.  After a command line is
           Alias substitution is repeated until the first word of the command  has
           no  alias.  If an alias substitution does not change the first word (as
           in the previous example) it is flagged to prevent a loop.  Other  loops
           are detected and cause an error.
    
           Some aliases are referred to by the shell; see Special aliases.
    
       Variable substitution
           The  shell  maintains a list of variables, each of which has as value a
           list of zero or more words.  The values of shell variables can be  dis-
           played  and  changed with the set and unset commands.  The system main-
           tains its own list of ''environment'' variables.   These  can  be  dis-
           played and changed with printenv, setenv and unsetenv.
    
           (+)  Variables  may  be  made read-only with 'set -r' (q.v.)  Read-only
           variables may not be modified or unset; attempting to do so will  cause
           an  error.  Once made read-only, a variable cannot be made writable, so
           'set -r' should be used with caution.  Environment variables cannot  be
           made read-only.
    
           Some  variables  are  set  by  the  shell  or  referred  to by it.  For
           instance, the argv variable is an image of the shell's  argument  list,
           and  words  of  this  variable's value are referred to in special ways.
           Some of the variables referred to by the shell are toggles;  the  shell
           does  not  care  what their value is, only whether they are set or not.
           For instance, the verbose variable is a  toggle  which  causes  command
           input  to  be  echoed.   The -v command line option sets this variable.
           Special shell variables lists all variables which are  referred  to  by
           the shell.
    
           Other  operations treat variables numerically.  The '@' command permits
           numeric calculations to be performed and the result assigned to a vari-
           able.   Variable  values  are,  however, always represented as (zero or
           more) strings.  For the purposes of numeric operations, the null string
           is considered to be zero, and the second and subsequent words of multi-
           word values are ignored.
    
           After the input line is aliased and parsed, and before each command  is
           executed,  variable  substitution is performed keyed by '$' characters.
           This expansion can be prevented by preceding the '$' with a '\'  except
           within  '"'s  where  it  always  occurs, and within '''s where it never
           occurs.  Strings quoted by ''' are interpreted later (see Command  sub-
           stitution  below) so '$' substitution does not occur there until later,
           if at all.  A '$' is passed unchanged if followed by a blank,  tab,  or
           end-of-line.
    
           Input/output redirections are recognized before variable expansion, and
           are variable expanded separately.   Otherwise,  the  command  name  and
           entire  argument  list  are expanded together.  It is thus possible for
           the first (command) word (to this point)  to  generate  more  than  one
           word,  the  first  of  which  becomes the command name, and the rest of
           which become arguments.
           $name
           ${name} Substitutes the words of the value of variable name, each sepa-
                   rated by a blank.  Braces insulate name from following  charac-
                   ters which would otherwise be part of it.  Shell variables have
                   names consisting of letters and digits starting with a  letter.
                   The  underscore  character  is considered a letter.  If name is
                   not a shell variable, but is set in the environment, then  that
                   value  is returned (but some of the other forms given below are
                   not available in this case).
           $name[selector]
           ${name[selector]}
                   Substitutes only the selected words from  the  value  of  name.
                   The  selector  is subjected to '$' substitution and may consist
                   of a single number or two numbers  separated  by  a  '-'.   The
                   first word of a variable's value is numbered '1'.  If the first
                   number of a range is omitted it defaults to '1'.  If  the  last
                   member  of  a  range  is  omitted it defaults to '$#name'.  The
                   selector '*' selects all words.  It is not an error for a range
                   to be empty if the second argument is omitted or in range.
           $0      Substitutes  the  name  of the file from which command input is
                   being read.  An error occurs if the name is not known.
           $number
           ${number}
                   Equivalent to '$argv[number]'.
           $*      Equivalent to '$argv', which is equivalent to '$argv[*]'.
    
           The ':' modifiers described  under  History  substitution,  except  for
           ':p',  can be applied to the substitutions above.  More than one may be
           used.  (+) Braces may be needed to  insulate  a  variable  substitution
           from a literal colon just as with History substitution (q.v.); any mod-
           ifiers must appear within the braces.
    
           The following substitutions can not be modified with ':' modifiers.
    
           $?name
           ${?name}
                   Substitutes the string '1' if name is set, '0' if it is not.
           $?0     Substitutes '1' if the current input filename is known, '0'  if
                   it is not.  Always '0' in interactive shells.
           $#name
           ${#name}
                   Substitutes the number of words in name.
           $#      Equivalent to '$#argv'.  (+)
           $%name
           ${%name}
                   Substitutes the number of characters in name.  (+)
           $%number
           ${%number}
                   Substitutes the number of characters in $argv[number].  (+)
           $?      Equivalent to '$status'.  (+)
           $$      Substitutes the (decimal) process number of the (parent) shell.
           $!      Substitutes the (decimal) process number of the last background
           The remaining substitutions are applied selectively to the arguments of
           builtin commands.  This means that portions of  expressions  which  are
           not  evaluated  are  not  subjected  to these expansions.  For commands
           which are not internal to the shell, the command  name  is  substituted
           separately from the argument list.  This occurs very late, after input-
           output redirection is performed, and in a child of the main shell.
    
       Command substitution
           Command substitution is indicated by a command enclosed  in  '''.   The
           output  from  such  a  command is broken into separate words at blanks,
           tabs and newlines, and null words are discarded.  The output  is  vari-
           able and command substituted and put in place of the original string.
    
           Command  substitutions  inside  double  quotes  ('"') retain blanks and
           tabs; only newlines force new words.  The single final newline does not
           force  a  new word in any case.  It is thus possible for a command sub-
           stitution to yield only part of a word, even if the command  outputs  a
           complete line.
    
           By  default, the shell since version 6.12 replaces all newline and car-
           riage return characters in the command by spaces.  If this is  switched
           off by unsetting csubstnonl, newlines separate commands as usual.
    
       Filename substitution
           If a word contains any of the characters '*', '?', '[' or '{' or begins
           with the character '~' it is a  candidate  for  filename  substitution,
           also  known  as  ''globbing''.  This word is then regarded as a pattern
           (''glob-pattern''), and replaced with an alphabetically sorted list  of
           file names which match the pattern.
    
           In matching filenames, the character '.' at the beginning of a filename
           or immediately following a '/', as well as the character  '/'  must  be
           matched  explicitly.   The  character '*' matches any string of charac-
           ters, including the null string.  The character '?' matches any  single
           character.   The  sequence  '[...]'  matches  any one of the characters
           enclosed.  Within '[...]',  a  pair  of  characters  separated  by  '-'
           matches any character lexically between the two.
    
           (+)  Some  glob-patterns  can be negated: The sequence '[^...]' matches
           any single character not specified by the characters and/or  ranges  of
           characters in the braces.
    
           An entire glob-pattern can also be negated with '^':
    
               > echo *
               bang crash crunch ouch
               > echo ^cr*
               bang ouch
    
           Glob-patterns  which  do not use '?', '*', or '[]' or which use '{}' or
           '~' (below) are not negated correctly.
    
           followed by a name consisting of letters, digits and '-' characters the
           shell  searches  for  a  user with that name and substitutes their home
           directory; thus '~ken' might expand to '/usr/ken' and '~ken/chmach'  to
           '/usr/ken/chmach'.   If  the  character  '~' is followed by a character
           other than a letter or '/' or appears elsewhere than at  the  beginning
           of  a  word,  it  is  left undisturbed.  A command like 'setenv MANPATH
           /usr/man:/usr/local/man:~/lib/man' does not, therefore, do home  direc-
           tory substitution as one might hope.
    
           It is an error for a glob-pattern containing '*', '?', '[' or '~', with
           or without '^', not to match any files.  However, only one pattern in a
           list  of  glob-patterns  must  match a file (so that, e.g., 'rm *.a *.c
           *.o' would fail only if there were no files in  the  current  directory
           ending  in '.a', '.c', or '.o'), and if the nonomatch shell variable is
           set a pattern (or list of  patterns)  which  matches  nothing  is  left
           unchanged rather than causing an error.
    
           The  noglob shell variable can be set to prevent filename substitution,
           and the expand-glob editor command, normally bound to  '^X-*',  can  be
           used to interactively expand individual filename substitutions.
    
       Directory stack substitution (+)
           The  directory stack is a list of directories, numbered from zero, used
           by the pushd, popd and dirs builtin commands (q.v.).  dirs  can  print,
           store in a file, restore and clear the directory stack at any time, and
           the savedirs and dirsfile shell variables  can  be  set  to  store  the
           directory  stack  automatically on logout and restore it on login.  The
           dirstack shell variable can be examined to see the directory stack  and
           set to put arbitrary directories into the directory stack.
    
           The character '=' followed by one or more digits expands to an entry in
           the directory stack.  The special case '=-' expands to the last  direc-
           tory in the stack.  For example,
    
               > dirs -v
               0       /usr/bin
               1       /usr/spool/uucp
               2       /usr/accts/sys
               > echo =1
               /usr/spool/uucp
               > echo =0/calendar
               /usr/bin/calendar
               > echo =-
               /usr/accts/sys
    
           The  noglob  and  nonomatch  shell variables and the expand-glob editor
           command apply to directory stack as well as filename substitutions.
    
       Other substitutions (+)
           There  are  several  more  transformations  involving  filenames,   not
           strictly related to the above but mentioned here for completeness.  Any
           filename may be expanded to a full  path  when  the  symlinks  variable
           the  command to be executed.  A series of simple commands joined by '|'
           characters forms a pipeline.  The output of each command in a  pipeline
           is connected to the input of the next.
    
           Simple  commands  and  pipelines may be joined into sequences with ';',
           and will be executed sequentially.  Commands and pipelines can also  be
           joined  into  sequences with '||' or '&&', indicating, as in the C lan-
           guage, that the second is to be executed only if  the  first  fails  or
           succeeds respectively.
    
           A  simple  command,  pipeline or sequence may be placed in parentheses,
           '()', to form a simple command, which may in turn be a component  of  a
           pipeline  or sequence.  A command, pipeline or sequence can be executed
           without waiting for it to terminate by following it with an '&'.
    
       Builtin and non-builtin command execution
           Builtin commands are executed within the shell.  If any component of  a
           pipeline except the last is a builtin command, the pipeline is executed
           in a subshell.
    
           Parenthesized commands are always executed in a subshell.
    
               (cd; pwd); pwd
    
           thus prints the home directory, leaving you where  you  were  (printing
           this after the home directory), while
    
               cd; pwd
    
           leaves  you  in  the  home  directory.  Parenthesized commands are most
           often used to prevent cd from affecting the current shell.
    
           When a command to be executed is found not to be a builtin command  the
           shell  attempts to execute the command via execve(2).  Each word in the
           variable path names a directory in which the shell will  look  for  the
           command.   If  the shell is not given a -f option, the shell hashes the
           names in these directories into an internal table so that it  will  try
           an  execve(2) in only a directory where there is a possibility that the
           command resides there.  This greatly speeds  command  location  when  a
           large  number of directories are present in the search path. This hash-
           ing mechanism is not used:
    
           1.  If hashing is turned explicitly off via unhash.
    
           2.  If the shell was given a -f argument.
    
           3.  For each directory component of path which does not  begin  with  a
               '/'.
    
           4.  If the command contains a '/'.
    
           In  the  above  four cases the shell concatenates each component of the
           it is of the form '#!interpreter arg ...'.  If it is, the shell  starts
           interpreter  with  the  given args and feeds the file to it on standard
           input.
    
       Input/output
           The standard input and standard output of a command may  be  redirected
           with the following syntax:
    
           < name  Open  file  name (which is first variable, command and filename
                   expanded) as the standard input.
           << word Read the shell input up to a line which is identical  to  word.
                   word  is not subjected to variable, filename or command substi-
                   tution, and each input line is compared to word before any sub-
                   stitutions  are done on this input line.  Unless a quoting '\',
                   '"', '' or ''' appears in word variable and  command  substitu-
                   tion  is  performed  on  the intervening lines, allowing '\' to
                   quote '$', '\' and '''.  Commands which  are  substituted  have
                   all  blanks, tabs, and newlines preserved, except for the final
                   newline which is dropped.  The resultant text is placed  in  an
                   anonymous temporary file which is given to the command as stan-
                   dard input.
           > name
           >! name
           >& name
           >&! name
                   The file name is used as standard output.  If the file does not
                   exist  then it is created; if the file exists, it is truncated,
                   its previous contents being lost.
    
                   If the shell variable noclobber is set, then the file must  not
                   exist  or  be  a  character  special  file (e.g., a terminal or
                   '/dev/null') or an error results.  This helps prevent  acciden-
                   tal  destruction  of  files.  In this case the '!' forms can be
                   used to suppress this check.
    
                   The forms involving '&' route the diagnostic  output  into  the
                   specified  file  as  well  as  the  standard  output.   name is
                   expanded in the same way as '<' input filenames are.
           >> name
           >>& name
           >>! name
           >>&! name
                   Like '>', but appends output to the end of name.  If the  shell
                   variable noclobber is set, then it is an error for the file not
                   to exist, unless one of the '!' forms is given.
    
           A command receives the environment in which the shell  was  invoked  as
           modified by the input-output parameters and the presence of the command
           in a pipeline.  Thus, unlike some previous shells, commands run from  a
           file  of  shell  commands have no access to the text of the commands by
           default; rather they receive the original standard input of the  shell.
           The '<<' mechanism should be used to present inline data.  This permits
    
       Features
           Having  described  how  the  shell accepts, parses and executes command
           lines, we now turn to a variety of its useful features.
    
       Control flow
           The shell contains a number of commands which can be used  to  regulate
           the  flow  of  control in command files (shell scripts) and (in limited
           but useful ways) from terminal input.  These commands  all  operate  by
           forcing the shell to reread or skip in its input and, due to the imple-
           mentation, restrict the placement of some of the commands.
    
           The foreach, switch, and while statements, as well as the  if-then-else
           form  of  the if statement, require that the major keywords appear in a
           single simple command on an input line as shown below.
    
           If the shell's input is not seekable, the shell buffers up input  when-
           ever a loop is being read and performs seeks in this internal buffer to
           accomplish the rereading implied by the loop.  (To the extent that this
           allows, backward gotos will succeed on non-seekable inputs.)
    
       Expressions
           The  if,  while and exit builtin commands use expressions with a common
           syntax.  The expressions can include any of the operators described  in
           the  next  three  sections.  Note that the @ builtin command (q.v.) has
           its own separate syntax.
    
       Logical, arithmetical and comparison operators
           These operators are similar to those of C and have the same precedence.
           They include
    
               ||  &&  |  ^  &  ==  !=  =~  !~  <=  >=
               <  > <<  >>  +  -  *  /  %  !  ~  (  )
    
           Here  the  precedence  increases to the right, '==' '!=' '=~' and '!~',
           '<=' '>=' '<' and '>', '<<' and '>>', '+' and  '-',  '*'  '/'  and  '%'
           being,  in  groups,  at  the same level.  When multiple operators which
           have same precedence are used in one expression,  calculation  must  be
           done  from  operator of right side.  The '==' '!=' '=~' and '!~' opera-
           tors compare their arguments as strings; all others operate on numbers.
           The  operators  '=~'  and  '!~'  are like '!=' and '==' except that the
           right hand side is a glob-pattern (see Filename  substitution)  against
           which  the left hand operand is matched.  This reduces the need for use
           of the switch builtin command in shell scripts when all that is  really
           needed is pattern matching.
    
           Null  or  missing  arguments  are  considered  '0'.  The results of all
           expressions are strings, which represent decimal numbers.  It is impor-
           tant  to note that no two components of an expression can appear in the
           same word; except when adjacent to components of expressions which  are
           syntactically  significant to the parser ('&' '|' '<' '>' '(' ')') they
           should be surrounded by spaces.
               r   Read access
               w   Write access
               x   Execute access
               X   Executable  in the path or shell builtin, e.g., '-X ls' and '-X
                   ls-F' are generally true, but '-X /bin/ls' is not (+)
               e   Existence
               o   Ownership
               z   Zero size
               s   Non-zero size (+)
               f   Plain file
               d   Directory
               l   Symbolic link (+) *
               b   Block special file (+)
               c   Character special file (+)
               p   Named pipe (fifo) (+) *
               S   Socket special file (+) *
               u   Set-user-ID bit is set (+)
               g   Set-group-ID bit is set (+)
               k   Sticky bit is set (+)
               t   file (which must be a digit) is an open file descriptor  for  a
                   terminal device (+)
               R   Has been migrated (convex only) (+)
               L   Applies  subsequent  operators in a multiple-operator test to a
                   symbolic link rather than to the file to which the link  points
                   (+) *
    
           file  is command and filename expanded and then tested to see if it has
           the specified relationship to the real user.  If file does not exist or
           is  inaccessible  or, for the operators indicated by '*', if the speci-
           fied file type does not exist on the current system, then all enquiries
           return false, i.e., '0'.
    
           These  operators may be combined for conciseness: '-xy file' is equiva-
           lent to '-x file && -y file'.  (+) For example, '-fx' is true  (returns
           '1') for plain executable files, but not for directories.
    
           L may be used in a multiple-operator test to apply subsequent operators
           to a symbolic link rather than to the file to which  the  link  points.
           For  example, '-lLo' is true for links owned by the invoking user.  Lr,
           Lw and Lx are always true for links and false for non-links.  L  has  a
           different  meaning  when it is the last operator in a multiple-operator
           test; see below.
    
           It is possible but not useful, and  sometimes  misleading,  to  combine
           operators  which  expect file to be a file with operators which do not,
           (e.g., X and t).  Following L with a non-file operator can lead to par-
           ticularly strange results.
    
           Other  operators  return  other information, i.e., not just '0' or '1'.
           (+) They have the same format as before; op may be one of
    
               A       Last file access time, as the number of seconds  since  the
               Pmode   Equivalent to '-P file & mode', e.g., '-P22  file'  returns
                       '22'  if  file  is  writable by group and other, '20' if by
                       group only, and '0' if by neither
               Pmode:  Like Pmode, with leading zero
               U       Numeric userid
               U:      Username, or the numeric userid if the username is unknown
               G       Numeric groupid
               G:      Groupname, or the  numeric  groupid  if  the  groupname  is
                       unknown
               Z       Size, in bytes
    
           Only one of these operators may appear in a multiple-operator test, and
           it must be the last.  Note that L has a different meaning at the end of
           and  elsewhere  in  a  multiple-operator  test.  Because '0' is a valid
           return value for many of these operators, they do not return  '0'  when
           they fail: most return '-1', and F returns ':'.
    
           If  the  shell  is  compiled  with POSIX defined (see the version shell
           variable), the result of a file inquiry is based on the permission bits
           of  the  file  and not on the result of the access(2) system call.  For
           example, if one tests a file with -w whose permissions would ordinarily
           allow writing but which is on a file system mounted read-only, the test
           will succeed in a POSIX shell but fail in a non-POSIX shell.
    
           File inquiry operators can also be evaluated with the filetest  builtin
           command (q.v.) (+).
    
       Jobs
           The  shell  associates  a  job with each pipeline.  It keeps a table of
           current jobs, printed by the jobs command, and assigns them small inte-
           ger  numbers.  When a job is started asynchronously with '&', the shell
           prints a line which looks like
    
               [1] 1234
    
           indicating that the job which was started asynchronously was job number
           1 and had one (top-level) process, whose process id was 1234.
    
           If  you are running a job and wish to do something else you may hit the
           suspend key (usually '^Z'), which sends a STOP signal  to  the  current
           job.  The shell will then normally indicate that the job has been 'Sus-
           pended' and print another prompt.  If the listjobs  shell  variable  is
           set,  all  jobs  will be listed like the jobs builtin command; if it is
           set to 'long' the listing will be in long format, like 'jobs -l'.   You
           can  then manipulate the state of the suspended job.  You can put it in
           the ''background'' with the bg command or run some other  commands  and
           eventually  bring  the  job back into the ''foreground'' with fg.  (See
           also the run-fg-editor editor command.)  A '^Z'  takes  effect  immedi-
           ately  and is like an interrupt in that pending output and unread input
           are discarded when it is typed.  The wait builtin  command  causes  the
           shell to wait for all background jobs to complete.
    
           '%'  introduces  a job name.  If you wish to refer to job number 1, you
           can name it as '%1'.  Just naming a job brings it  to  the  foreground;
           thus  '%1' is a synonym for 'fg %1', bringing job 1 back into the fore-
           ground.  Similarly, saying '%1 &' resumes job 1 in the background, just
           like  'bg %1'.  A job can also be named by an unambiguous prefix of the
           string typed in to start it: '%ex' would normally restart  a  suspended
           ex(1)  job,  if there were only one suspended job whose name began with
           the string 'ex'.  It is also possible to say '%?string'  to  specify  a
           job whose text contains string, if there is only one such job.
    
           The shell maintains a notion of the current and previous jobs.  In out-
           put pertaining to jobs, the current job is marked with a  '+'  and  the
           previous  job with a '-'.  The abbreviations '%+', '%', and (by analogy
           with the syntax of the history mechanism) '%%' all refer to the current
           job, and '%-' refers to the previous job.
    
           The job control mechanism requires that the stty(1) option 'new' be set
           on some systems.  It is an artifact from a 'new' implementation of  the
           tty  driver  which  allows  generation of interrupt characters from the
           keyboard to tell jobs to stop.  See stty(1) and the setty builtin  com-
           mand for details on setting options in the new tty driver.
    
       Status reporting
           The shell learns immediately whenever a process changes state.  It nor-
           mally informs you whenever a job becomes blocked  so  that  no  further
           progress  is  possible, but only right before it prints a prompt.  This
           is done so that it does not otherwise disturb your work.  If,  however,
           you  set  the  shell variable notify, the shell will notify you immedi-
           ately of changes of status in background jobs.  There is also  a  shell
           command  notify which marks a single process so that its status changes
           will be immediately reported.  By default notify marks the current pro-
           cess; simply say 'notify' after starting a background job to mark it.
    
           When  you  try  to  leave the shell while jobs are stopped, you will be
           warned that 'There are suspended jobs.' You may use the jobs command to
           see  what  they  are.  If you do this or immediately try to exit again,
           the shell will not warn you a second time, and the suspended jobs  will
           be terminated.
    
       Automatic, periodic and timed events (+)
           There are various ways to run commands and take other actions automati-
           cally at various times in the ''life cycle'' of the  shell.   They  are
           summarized  here, and described in detail under the appropriate Builtin
           commands, Special shell variables and Special aliases.
    
           The sched builtin command puts commands in a scheduled-event  list,  to
           be executed by the shell at a given time.
    
           The  beepcmd,  cwdcmd,  periodic,  precmd,  postcmd, and jobcmd Special
           aliases can be set, respectively, to execute commands  when  the  shell
           wants  to ring the bell, when the working directory changes, every tpe-
           riod minutes, before each prompt, before each  command  gets  executed,
           The time shell variable can be set to execute the time builtin  command
           after the completion of any process that takes more than a given number
           of CPU seconds.
    
           The watch and who shell variables can be set to  report  when  selected
           users log in or out, and the log builtin command reports on those users
           at any time.
    
       Native Language System support (+)
           The shell is eight bit clean (if so compiled;  see  the  version  shell
           variable)  and  thus  supports  character sets needing this capability.
           NLS support differs depending on whether or not the shell was  compiled
           to  use  the  system's NLS (again, see version).  In either case, 7-bit
           ASCII is the default character code (e.g., the classification of  which
           characters  are  printable)  and  sorting,  and  changing  the  LANG or
           LC_CTYPE environment variables causes a check for possible  changes  in
           these respects.
    
           When  using  the  system's  NLS, the setlocale(3) function is called to
           determine appropriate character code/classification and sorting  (e.g.,
           a  'en_CA.UTF-8'  would yield "UTF-8" as a character code).  This func-
           tion typically examines the LANG and  LC_CTYPE  environment  variables;
           refer  to the system documentation for further details.  When not using
           the system's NLS, the shell simulates  it  by  assuming  that  the  ISO
           8859-1  character  set is used whenever either of the LANG and LC_CTYPE
           variables are set, regardless of their values.  Sorting is not affected
           for the simulated NLS.
    
           In addition, with both real and simulated NLS, all printable characters
           in the range \200-\377, i.e., those  that  have  M-char  bindings,  are
           automatically  rebound to self-insert-command.  The corresponding bind-
           ing for the escape-char sequence, if any, is left alone.  These charac-
           ters are not rebound if the NOREBIND environment variable is set.  This
           may be useful for the simulated NLS  or  a  primitive  real  NLS  which
           assumes  full  ISO 8859-1.  Otherwise, all M-char bindings in the range
           \240-\377 are effectively undone.  Explicitly  rebinding  the  relevant
           keys with bindkey is of course still possible.
    
           Unknown  characters (i.e., those that are neither printable nor control
           characters) are printed in the format \nnn.  If the tty is not in 8 bit
           mode,  other  8  bit characters are printed by converting them to ASCII
           and using standout mode.  The shell never changes the 7/8 bit  mode  of
           the  tty  and tracks user-initiated changes of 7/8 bit mode.  NLS users
           (or, for that matter, those who want to use a meta  key)  may  need  to
           explicitly  set  the  tty in 8 bit mode through the appropriate stty(1)
           command in, e.g., the ~/.login file.
    
       OS variant support (+)
           A number of new builtin commands are provided to  support  features  in
           particular  operating  systems.   All  are  described  in detail in the
           Builtin commands section.
    
           Under Masscomp/RTU and Harris CX/UX, universe sets the universe.
    
           Under Harris CX/UX, ucb or att runs a command under the specified  uni-
           verse.
    
           Under Convex/OS, warp prints or sets the universe.
    
           The  VENDOR, OSTYPE and MACHTYPE environment variables indicate respec-
           tively the vendor, operating system and  machine  type  (microprocessor
           class  or  machine model) of the system on which the shell thinks it is
           running.  These are particularly useful when sharing one's home  direc-
           tory between several types of machines; one can, for example,
    
               set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)
    
           in  one's ~/.login and put executables compiled for each machine in the
           appropriate directory.
    
           The version shell variable indicates what options were chosen when  the
           shell was compiled.
    
           Note  also  the  newgrp builtin, the afsuser and echo_style shell vari-
           ables and the system-dependent locations of  the  shell's  input  files
           (see FILES).
    
       Signal handling
           Login  shells  ignore  interrupts when reading the file ~/.logout.  The
           shell ignores quit signals unless started with -q.  Login shells  catch
           the terminate signal, but non-login shells inherit the terminate behav-
           ior from their parents.  Other signals have the values which the  shell
           inherited from its parent.
    
           In  shell scripts, the shell's handling of interrupt and terminate sig-
           nals can be controlled with onintr, and its handling of hangups can  be
           controlled with hup and nohup.
    
           The  shell  exits on a hangup (see also the logout shell variable).  By
           default, the shell's children do too, but the shell does not send  them
           a hangup when it exits.  hup arranges for the shell to send a hangup to
           a child when it exits, and nohup sets a child to ignore hangups.
    
       Terminal management (+)
           The shell uses  three  different  sets  of  terminal  (''tty'')  modes:
           'edit',  used  when editing, 'quote', used when quoting literal charac-
           ters, and 'execute', used when executing  commands.   The  shell  holds
           some settings in each mode constant, so commands which leave the tty in
           a confused state do not interfere  with  the  shell.   The  shell  also
           matches  changes  in the speed and padding of the tty.  The list of tty
           modes that are kept constant can be  examined  and  modified  with  the
           setty  builtin.  Note that although the editor uses CBREAK mode (or its
           equivalent), it takes typed-ahead characters anyway.
    
    
           %job &  A synonym for the bg builtin command.
    
           :       Does nothing, successfully.
    
           @
           @ name = expr
           @ name[index] = expr
           @ name++|--
           @ name[index]++|--
                   The first form prints the values of all shell variables.
    
                   The second form assigns the value of expr to name.   The  third
                   form  assigns  the  value  of expr to the index'th component of
                   name; both name and its index'th component must already  exist.
    
                   expr  may  contain  the  operators '*', '+', etc., as in C.  If
                   expr contains '<', '>', '&' or '' then at least  that  part  of
                   expr  must be placed within '()'.  Note that the syntax of expr
                   has nothing to do with that described under Expressions.
    
                   The fourth and fifth forms increment ('++') or decrement ('--')
                   name or its index'th component.
    
                   The space between '@' and name is required.  The spaces between
                   name and '=' and between '=' and expr are optional.  Components
                   of expr must be separated by spaces.
    
           alias [name [wordlist]]
                   Without  arguments,  prints all aliases.  With name, prints the
                   alias for name.  With name and wordlist,  assigns  wordlist  as
                   the  alias  of  name.  wordlist is command and filename substi-
                   tuted.  name may not be 'alias' or  'unalias'.   See  also  the
                   unalias builtin command.
    
           alloc   Shows  the  amount of dynamic memory acquired, broken down into
                   used and free memory.  With an argument  shows  the  number  of
                   free  and  used  blocks  in each size category.  The categories
                   start at size 8 and double at each step.  This command's output
                   may  vary  across  system types, because systems other than the
                   VAX may use a different memory allocator.
    
           bg [%job ...]
                   Puts the specified jobs (or,  without  arguments,  the  current
                   job)  into  the  background,  continuing each if it is stopped.
                   job may be a number, a string, '', '%', '+' or '-' as described
                   under Jobs.
    
           bindkey [-l|-d|-e|-v|-u] (+)
           bindkey [-a] [-b] [-k] [-r] [--] key (+)
           bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
                   Without  options,  the  first form lists all bound keys and the
                       written F-string (e.g., 'F-string'), or an extended  prefix
                       key written X-character (e.g., 'X-A').
                   -k  key  is interpreted as a symbolic arrow key name, which may
                       be one of 'down', 'up', 'left' or 'right'.
                   -r  Removes key's binding.  Be careful: 'bindkey -r'  does  not
                       bind key to self-insert-command (q.v.), it unbinds key com-
                       pletely.
                   -c  command is interpreted as a  builtin  or  external  command
                       instead of an editor command.
                   -s  command  is taken as a literal string and treated as termi-
                       nal input when key is typed.  Bound  keys  in  command  are
                       themselves reinterpreted, and this continues for ten levels
                       of interpretation.
                   --  Forces a break from option processing, so the next word  is
                       taken as key even if it begins with '-'.
                   -u (or any invalid option)
                       Prints a usage message.
    
                   key  may  be  a  single character or a string.  If a command is
                   bound to a string, the first character of the string  is  bound
                   to  sequence-lead-in and the entire string is bound to the com-
                   mand.
    
                   Control characters in key can be literal (they can be typed  by
                   preceding  them with the editor command quoted-insert, normally
                   bound to '^V') or written caret-character  style,  e.g.,  '^A'.
                   Delete is written '^?'  (caret-question mark).  key and command
                   can contain backslashed escape sequences (in the style of  Sys-
                   tem V echo(1)) as follows:
    
                       \a      Bell
                       \b      Backspace
                       \e      Escape
                       \f      Form feed
                       \n      Newline
                       \r      Carriage return
                       \t      Horizontal tab
                       \v      Vertical tab
                       \nnn    The ASCII character corresponding to the octal num-
                               ber nnn
    
                   '\' nullifies the special meaning of the  following  character,
                   if it has any, notably '\' and '^'.
    
           bs2cmd bs2000-command (+)
                   Passes  bs2000-command  to  the  BS2000 command interpreter for
                   execution. Only non-interactive commands can be  executed,  and
                   it  is  not  possible to execute any command that would overlay
                   the image of the current process, like /EXECUTE or /CALL-PROCE-
                   DURE. (BS2000 only)
    
           break   Causes execution to resume after the end of the nearest enclos-
    
           cd [-p] [-l] [-n|-v] [name]
                   If  a  directory  name  is  given,  changes the shell's working
                   directory to name.  If not, changes to home.  If name is '-' it
                   is  interpreted  as  the  previous working directory (see Other
                   substitutions).  (+) If name is not a subdirectory of the  cur-
                   rent  directory  (and  does not begin with '/', './' or '../'),
                   each component of the variable cdpath is checked to see  if  it
                   has  a  subdirectory name.  Finally, if all else fails but name
                   is a shell variable whose value begins with '/', then  this  is
                   tried to see if it is a directory.
    
                   With -p, prints the final directory stack, just like dirs.  The
                   -l, -n and -v flags have the same effect on cd as on dirs,  and
                   they imply -p.  (+)
    
                   See also the implicitcd shell variable.
    
           chdir   A synonym for the cd builtin command.
    
           complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
                   Without  arguments, lists all completions.  With command, lists
                   completions for command.  With command and word  etc.,  defines
                   completions.
    
                   command may be a full command name or a glob-pattern (see File-
                   name substitution).  It can begin with  '-'  to  indicate  that
                   completion should be used only when command is ambiguous.
    
                   word specifies which word relative to the current word is to be
                   completed, and may be one of the following:
    
                       c   Current-word completion.   pattern  is  a  glob-pattern
                           which  must  match the beginning of the current word on
                           the command line.  pattern is ignored  when  completing
                           the current word.
                       C   Like  c,  but includes pattern when completing the cur-
                           rent word.
                       n   Next-word completion.  pattern is a glob-pattern  which
                           must  match  the  beginning of the previous word on the
                           command line.
                       N   Like n, but must match the beginning of  the  word  two
                           before the current word.
                       p   Position-dependent  completion.   pattern  is a numeric
                           range, with the same syntax used to index  shell  vari-
                           ables, which must include the current word.
    
                   list,  the list of possible completions, may be one of the fol-
                   lowing:
    
                       a       Aliases
                       b       Bindings (editor commands)
                       S       Signals
                       t       Plain (''text'') files
                       T       Plain  (''text'')  files  which begin with the sup-
                               plied path prefix
                       v       Any variables
                       u       Usernames
                       x       Like n, but  prints  select  when  list-choices  is
                               used.
                       X       Completions
                       $var    Words from the variable var
                       (...)   Words from the given list
                       '...'   Words from the output of command
    
                   select  is an optional glob-pattern.  If given, words from only
                   list that match select are considered  and  the  fignore  shell
                   variable  is  ignored.   The last three types of completion may
                   not have a select pattern, and x uses select as an  explanatory
                   message when the list-choices editor command is used.
    
                   suffix  is  a  single  character to be appended to a successful
                   completion.  If null, no character is appended.  If omitted (in
                   which  case  the fourth delimiter can also be omitted), a slash
                   is appended to directories and a space to other words.
    
                   command invoked from '...' version has  additional  environment
                   variable  set,  the  variable name is COMMAND_LINE and contains
                   (as its name indicates) contents of the current (already  typed
                   in)  command  line.  One  can  examine  and use contents of the
                   COMMAND_LINE variable  in  her  custom  script  to  build  more
                   sophisticated  completions  (see completion for svn(1) included
                   in this package).
    
                   Now for some examples.  Some commands take only directories  as
                   arguments, so there's no point completing plain files.
    
                       > complete cd 'p/1/d/'
    
                   completes  only  the  first  word following 'cd' ('p/1') with a
                   directory.  p-type completion can also be used to  narrow  down
                   command completion:
    
                       > co[^D]
                       complete compress
                       > complete -co* 'p/0/(compress)/'
                       > co[^D]
                       > compress
    
                   This completion completes commands (words in position 0, 'p/0')
                   which begin with 'co' (thus matching 'co*') to 'compress'  (the
                   only  word  in  the list).  The leading '-' indicates that this
                   completion is to be used with only ambiguous commands.
    
                       > complete alias 'p/1/a/'
                       > complete man 'p/*/c/'
                       > complete set 'p/1/s/'
                       > complete true 'p/1/x:Truth has no options./'
    
                   These complete words following 'alias' with aliases, 'man' with
                   commands,  and 'set' with shell variables.  'true' doesn't have
                   any options, so x does nothing when completion is attempted and
                   prints  'Truth  has  no  options.'  when completion choices are
                   listed.
    
                   Note that the man example, and several  other  examples  below,
                   could just as well have used 'c/*' or 'n/*' as 'p/*'.
    
                   Words  can be completed from a variable evaluated at completion
                   time,
    
                       > complete ftp 'p/1/$hostnames/'
                       > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu)
                       > ftp [^D]
                       rtfm.mit.edu tesla.ee.cornell.edu
                       > ftp [^C]
                       >  set  hostnames  =   (rtfm.mit.edu   tesla.ee.cornell.edu
                       uunet.uu.net)
                       > ftp [^D]
                       rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net
    
                   or from a command run at completion time:
    
                       > complete kill 'p/*/'ps | awk \{print\ \$1\}'/'
                       > kill -9 [^D]
                       23113 23377 23380 23406 23429 23529 23530 PID
    
                   Note  that the complete command does not itself quote its argu-
                   ments, so the braces, space and '$' in  '{print  $1}'  must  be
                   quoted explicitly.
    
                   One command can have multiple completions:
    
                       > complete dbx 'p/2/(core)/' 'p/*/c/'
    
                   completes the second argument to 'dbx' with the word 'core' and
                   all other arguments with commands.  Note  that  the  positional
                   completion   is  specified  before  the  next-word  completion.
                   Because completions are evaluated from left to  right,  if  the
                   next-word completion were specified first it would always match
                   and the positional completion would never be executed.  This is
                   a common mistake when defining a completion.
    
                   The  select  pattern  is useful when a command takes files with
                   only particular forms as arguments.  For example,
    
                   The 'C', 'D', 'F' and 'T' lists are like 'c', 'd', 'f' and  't'
                   respectively,  but  they use the select argument in a different
                   way: to restrict completion to files beginning with a  particu-
                   lar path prefix.  For example, the Elm mail program uses '=' as
                   an abbreviation for one's mail directory.  One might use
    
                       > complete elm c@=@F:$HOME/Mail/@
    
                   to complete 'elm -f =' as if it were 'elm  -f  ~/Mail/'.   Note
                   that  we  used  '@'  instead of '/' to avoid confusion with the
                   select argument, and we used '$HOME'  instead  of  '~'  because
                   home  directory  substitution  works at only the beginning of a
                   word.
    
                   suffix is used to add a nonstandard suffix (not  space  or  '/'
                   for directories) to completed words.
    
                       > complete finger 'c/*@/$hostnames/' 'p/1/u/@'
    
                   completes arguments to 'finger' from the list of users, appends
                   an '@', and then completes after the '@' from  the  'hostnames'
                   variable.   Note  again  the order in which the completions are
                   specified.
    
                   Finally, here's a complex example for inspiration:
    
                       > complete find \
                       'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
                       ?n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
                       'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
                       'n/-type/(b c d f l p s)/' \
                       ?c/-/(name newer cpio ncpio exec ok user \
                       group fstype type atime ctime depth inum \
                       ls mtime nogroup nouser perm print prune \
                       size xdev)/' \
                       'p/*/d/'
    
                   This completes words following '-name',  '-newer',  '-cpio'  or
                   'ncpio'  (note  the pattern which matches both) to files, words
                   following '-exec' or '-ok' to commands, words following  'user'
                   and  'group' to users and groups respectively and words follow-
                   ing '-fstype' or '-type' to members of  the  given  lists.   It
                   also  completes  the  switches  themselves  from the given list
                   (note the use of c-type completion) and completes anything  not
                   otherwise completed to a directory.  Whew.
    
                   Remember  that  programmed  completions are ignored if the word
                   being completed is a tilde substitution (beginning with '~') or
                   a  variable  (beginning with '$').  complete is an experimental
                   feature, and the syntax may change in future  versions  of  the
                   shell.  See also the uncomplete builtin command.
    
                   is expanded explicitly to home or  the  pathname  of  the  home
                   directory  for  user  name.   (+)  With -n, entries are wrapped
                   before they reach the edge of the screen.  (+) With -v, entries
                   are  printed  one  per line, preceded by their stack positions.
                   (+) If more than one of -n or -v is given, -v takes precedence.
                   -p is accepted but does nothing.
    
                   With  -S, the second form saves the directory stack to filename
                   as a series of cd and  pushd  commands.   With  -L,  the  shell
                   sources  filename,  which  is presumably a directory stack file
                   saved by the -S option or the savedirs  mechanism.   In  either
                   case,  dirsfile is used if filename is not given and ~/.cshdirs
                   is used if dirsfile is unset.
    
                   Note that login shells  do  the  equivalent  of  'dirs  -L'  on
                   startup  and,  if  savedirs  is  set, 'dirs -S' before exiting.
                   Because only ~/.tcshrc is normally sourced  before  ~/.cshdirs,
                   dirsfile should be set in ~/.tcshrc rather than ~/.login.
    
                   The last form clears the directory stack.
    
           echo [-n] word ...
                   Writes  each  word to the shell's standard output, separated by
                   spaces and terminated with a  newline.   The  echo_style  shell
                   variable  may  be  set to emulate (or not) the flags and escape
                   sequences of the BSD and/or System  V  versions  of  echo;  see
                   echo(1).
    
           echotc [-sv] arg ... (+)
                   Exercises  the  terminal capabilities (see termcap(5)) in args.
                   For example, 'echotc home' sends the cursor to the  home  posi-
                   tion,  'echotc  cm  3  10' sends it to column 3 and row 10, and
                   'echotc ts 0; echo "This is a test."; echotc fs'  prints  "This
                   is a test."  in the status line.
    
                   If arg is 'baud', 'cols', 'lines', 'meta' or 'tabs', prints the
                   value of that capability ("yes" or  "no"  indicating  that  the
                   terminal does or does not have that capability).  One might use
                   this to make the output from a shell  script  less  verbose  on
                   slow  terminals, or limit command output to the number of lines
                   on the screen:
    
                       > set history='echotc lines'
                       > @ history--
    
                   Termcap strings may contain wildcards which will not echo  cor-
                   rectly.   One  should  use  double  quotes when setting a shell
                   variable to a terminal capability string, as in  the  following
                   example that places the date in the status line:
    
                       > set tosl="'echotc ts 0'"
                       > set frsl="'echotc fs'"
    
                   is  usually used to execute commands generated as the result of
                   command or variable substitution, because parsing occurs before
                   these substitutions.  See tset(1) for a sample use of eval.
    
           exec command
                   Executes the specified command in place of the current shell.
    
           exit [expr]
                   The shell exits either with the value of the specified expr (an
                   expression, as described under Expressions) or,  without  expr,
                   with the value 0.
    
           fg [%job ...]
                   Brings  the  specified jobs (or, without arguments, the current
                   job) into the foreground, continuing each  if  it  is  stopped.
                   job may be a number, a string, '', '%', '+' or '-' as described
                   under Jobs.  See also the run-fg-editor editor command.
    
           filetest -op file ... (+)
                   Applies op (which is a file inquiry operator as described under
                   File inquiry operators) to each file and returns the results as
                   a space-separated list.
    
           foreach name (wordlist)
           ...
           end     Successively sets the variable name to each member of  wordlist
                   and  executes the sequence of commands between this command and
                   the matching end.  (Both foreach and end must appear  alone  on
                   separate  lines.)   The builtin command continue may be used to
                   continue the loop prematurely and the builtin command break  to
                   terminate  it  prematurely.  When this command is read from the
                   terminal, the loop is read once prompting with 'foreach? '  (or
                   prompt2)  before  any  statements in the loop are executed.  If
                   you make a mistake typing in a loop at the terminal you can rub
                   it out.
    
           getspath (+)
                   Prints the system execution path.  (TCF only)
    
           getxvers (+)
                   Prints the experimental version prefix.  (TCF only)
    
           glob wordlist
                   Like  echo,  but the '-n' parameter is not recognized and words
                   are delimited by null characters in  the  output.   Useful  for
                   programs  which wish to use the shell to filename expand a list
                   of words.
    
           goto word
                   word is filename and command-substituted to yield a  string  of
                   the  form 'label'.  The shell rewinds its input as much as pos-
                   sible, searches for a line of the form 'label:', possibly  pre-
    
           history -S|-L|-M [filename] (+)
           history -c (+)
                   The  first  form  prints the history event list.  If n is given
                   only the n most recent events are printed or saved.   With  -h,
                   the  history list is printed without leading numbers.  If -T is
                   specified, timestamps are printed also in comment form.   (This
                   can be used to produce files suitable for loading with 'history
                   -L' or 'source -h'.)  With -r, the order of  printing  is  most
                   recent first rather than oldest first.
    
                   With  -S,  the  second form saves the history list to filename.
                   If the first word of the savehist shell variable is  set  to  a
                   number,  at most that many lines are saved.  If the second word
                   of savehist is set to 'merge', the history list is merged  with
                   the  existing history file instead of replacing it (if there is
                   one) and sorted by time stamp.  (+) Merging is intended for  an
                   environment  like  the  X  Window System with several shells in
                   simultaneous use.  Currently it succeeds only when  the  shells
                   quit nicely one after another.
    
                   With -L, the shell appends filename, which is presumably a his-
                   tory list saved by the -S option or the savehist mechanism,  to
                   the  history list.  -M is like -L, but the contents of filename
                   are merged into the history list and sorted by  timestamp.   In
                   either  case,  histfile  is  used  if filename is not given and
                   ~/.history is used if  histfile  is  unset.   'history  -L'  is
                   exactly  like  'source  -h'  except  that it does not require a
                   filename.
    
                   Note that login shells do the equivalent  of  'history  -L'  on
                   startup  and,  if savehist is set, 'history -S' before exiting.
                   Because only ~/.tcshrc is normally sourced  before  ~/.history,
                   histfile should be set in ~/.tcshrc rather than ~/.login.
    
                   If  histlit  is  set, the first and second forms print and save
                   the literal (unexpanded) form of the history list.
    
                   The last form clears the history list.
    
           hup [command] (+)
                   With command, runs command such that it will exit on  a  hangup
                   signal  and  arranges  for the shell to send it a hangup signal
                   when the shell exits.  Note that commands  may  set  their  own
                   response  to  hangups,  overriding  hup.   Without  an argument
                   (allowed in only a shell script), causes the shell to exit on a
                   hangup  for  the remainder of the script.  See also Signal han-
                   dling and the nohup builtin command.
    
           if (expr) command
                   If expr (an expression, as described under Expressions)  evalu-
                   ates  true, then command is executed.  Variable substitution on
                   command happens early, at the same time it does for the rest of
                   to  the  second  else are executed, etc.  Any number of else-if
                   pairs are possible; only one endif is needed.  The else part is
                   likewise  optional.   (The  words else and endif must appear at
                   the beginning of input lines; the if must appear alone  on  its
                   input line or after an else.)
    
           inlib shared-library ... (+)
                   Adds  each shared-library to the current environment.  There is
                   no way to remove a shared library.  (Domain/OS only)
    
           jobs [-l]
                   Lists the active jobs.  With -l, lists process IDs in  addition
                   to  the normal information.  On TCF systems, prints the site on
                   which each job is executing.
    
           kill [-s signal] %job|pid ...
           kill -l The first and second forms sends the specified signal  (or,  if
                   none  is  given,  the TERM (terminate) signal) to the specified
                   jobs or processes.  job may be a number, a string, '', '%', '+'
                   or  '-'  as  described under Jobs.  Signals are either given by
                   number or by name (as given in /usr/include/signal.h,  stripped
                   of  the  prefix  'SIG').   There is no default job; saying just
                   'kill' does not send a signal to the current job.  If the  sig-
                   nal  being  sent  is TERM (terminate) or HUP (hangup), then the
                   job or process is sent a CONT (continue) signal as  well.   The
                   third form lists the signal names.
    
           limit [-h] [resource [maximum-use]]
                   Limits  the consumption by the current process and each process
                   it creates to not individually exceed maximum-use on the speci-
                   fied  resource.   If  no maximum-use is given, then the current
                   limit is printed; if no resource is given, then all limitations
                   are  given.   If the -h flag is given, the hard limits are used
                   instead of the current limits.  The hard limits impose a  ceil-
                   ing  on  the values of the current limits.  Only the super-user
                   may raise the hard limits, but a user may lower  or  raise  the
                   current limits within the legal range.
    
                   Controllable  resources  currently include (if supported by the
                   OS):
    
                   cputime
                          the maximum number of cpu-seconds to  be  used  by  each
                          process
    
                   filesize
                          the largest single file which can be created
    
                   datasize
                          the  maximum growth of the data+stack region via sbrk(2)
                          beyond the end of the program text
    
                          the maximum amount of memory a process may allocate  per
                          brk() system call
    
                   descriptors or openfiles
                          the maximum number of open files for this process
    
                   concurrency
                          the maximum number of threads for this process
    
                   memorylocked
                          the  maximum  size  which a process may lock into memory
                          using mlock(2)
    
                   maxproc
                          the maximum number of simultaneous  processes  for  this
                          user id
    
                   sbsize the maximum size of socket buffer usage for this user
    
                   swapsize
                          the  maximum  amount  of swap space reserved or used for
                          this user
    
                   maximum-use may be given as a (floating point or integer)  num-
                   ber  followed  by  a  scale  factor.  For all limits other than
                   cputime the default scale is 'k' or 'kilobytes' (1024 bytes); a
                   scale  factor  of  'm'  or  'megabytes'  may also be used.  For
                   cputime the default scaling is 'seconds', while 'm' for minutes
                   or  'h' for hours, or a time of the form 'mm:ss' giving minutes
                   and seconds may be used.
    
                   For both resource names and scale factors, unambiguous prefixes
                   of the names suffice.
    
           log (+) Prints  the watch shell variable and reports on each user indi-
                   cated in watch who is logged in, regardless of when  they  last
                   logged in.  See also watchlog.
    
           login   Terminates  a  login  shell,  replacing  it with an instance of
                   /bin/login. This is one way to log off, included  for  compati-
                   bility with sh(1).
    
           logout  Terminates  a  login  shell.  Especially useful if ignoreeof is
                   set.
    
           ls-F [-switch ...] [file ...] (+)
                   Lists files like 'ls -F', but much faster.  It identifies  each
                   type of special file in the listing with a special character:
    
                   /   Directory
                   *   Executable
                   #   Block device
                   &   Symbolic link to nowhere
    
                   listlinks also slows down ls-F and  causes  partitions  holding
                   files pointed to by symbolic links to be mounted.
    
                   If  the  listflags shell variable is set to 'x', 'a' or 'A', or
                   any combination thereof (e.g., 'xA'), they are used as flags to
                   ls-F, making it act like 'ls -xF', 'ls -Fa', 'ls -FA' or a com-
                   bination (e.g., 'ls -FxA').  On machines where 'ls -C'  is  not
                   the default, ls-F acts like 'ls -CF', unless listflags contains
                   an 'x', in which case it acts like 'ls -xF'.  ls-F  passes  its
                   arguments  to  ls(1)  if it is given any switches, so 'alias ls
                   ls-F' generally does the right thing.
    
                   The ls-F builtin can list files using different colors  depend-
                   ing  on the filetype or extension.  See the color tcsh variable
                   and the LS_COLORS environment variable.
    
           migrate [-site] pid|%jobid ... (+)
           migrate -site (+)
                   The first form migrates the process or job to the  site  speci-
                   fied  or  the  default site determined by the system path.  The
                   second form is equivalent to 'migrate -site  $$':  it  migrates
                   the current process to the specified site.  Migrating the shell
                   itself can cause unexpected behavior, because  the  shell  does
                   not like to lose its tty.  (TCF only)
    
           newgrp [-] group (+)
                   Equivalent  to 'exec newgrp'; see newgrp(1).  Available only if
                   the shell was so compiled; see the version shell variable.
    
           nice [+number] [command]
                   Sets the scheduling priority for the shell to number, or, with-
                   out  number, to 4.  With command, runs command at the appropri-
                   ate priority.  The greater the number, the less cpu the process
                   gets.   The  super-user  may specify negative priority by using
                   'nice -number ...'.  Command is always executed in a sub-shell,
                   and the restrictions placed on commands in simple if statements
                   apply.
    
           nohup [command]
                   With command, runs command such that it will ignore hangup sig-
                   nals.   Note  that  commands  may  set  their  own  response to
                   hangups, overriding nohup.  Without  an  argument  (allowed  in
                   only  a  shell  script), causes the shell to ignore hangups for
                   the remainder of the script.  See also Signal handling and  the
                   hup builtin command.
    
           notify [%job ...]
                   Causes  the  shell  to  notify the user asynchronously when the
                   status of any of the specified jobs (or, without %job, the cur-
                   rent  job) changes, instead of waiting until the next prompt as
                   anyway.
    
           popd [-p] [-l] [-n|-v] [+n]
                   Without  arguments, pops the directory stack and returns to the
                   new top directory.  With a number '+n', discards the n'th entry
                   in the stack.
    
                   Finally,  all  forms  of  popd print the final directory stack,
                   just like dirs.  The pushdsilent shell variable can be  set  to
                   prevent  this and the -p flag can be given to override pushdsi-
                   lent.  The -l, -n and -v flags have the same effect on popd  as
                   on dirs.  (+)
    
           printenv [name] (+)
                   Prints  the  names  and values of all environment variables or,
                   with name, the value of the environment variable name.
    
           pushd [-p] [-l] [-n|-v] [name|+n]
                   Without arguments, exchanges the top two elements of the direc-
                   tory  stack.   If  pushdtohome  is set, pushd without arguments
                   does 'pushd ~', like cd.  (+) With  name,  pushes  the  current
                   working directory onto the directory stack and changes to name.
                   If name is '-' it is interpreted as the previous working direc-
                   tory (see Filename substitution).  (+) If dunique is set, pushd
                   removes any instances of name from the stack before pushing  it
                   onto  the  stack.  (+) With a number '+n', rotates the nth ele-
                   ment of the directory stack around to be the  top  element  and
                   changes  to  it.   If  dextract  is  set,  however,  'pushd +n'
                   extracts the nth directory, pushes it onto the top of the stack
                   and changes to it.  (+)
    
                   Finally,  all  forms  of pushd print the final directory stack,
                   just like dirs.  The pushdsilent shell variable can be  set  to
                   prevent  this and the -p flag can be given to override pushdsi-
                   lent.  The -l, -n and -v flags have the same effect on pushd as
                   on dirs.  (+)
    
           rehash  Causes  the internal hash table of the contents of the directo-
                   ries in the path variable to be recomputed.  This is needed  if
                   new  commands  are  added  to directories in path while you are
                   logged in.  This should be necessary only if you  add  commands
                   to  one  of  your  own  directories, or if a systems programmer
                   changes the contents of one of the  system  directories.   Also
                   flushes the cache of home directories built by tilde expansion.
    
           repeat count command
                   The specified command, which is subject to  the  same  restric-
                   tions  as  the  command  in the one line if statement above, is
                   executed count times.  I/O  redirections  occur  exactly  once,
                   even if count is 0.
    
           rootnode //nodename (+)
                   time may be in 12-hour AM/PM format
    
                       > sched 5pm set prompt='[%h] It\'s after 5; go home: >'
    
                   or may be relative to the current time:
    
                       > sched +2:15 /usr/lib/uucp/uucico -r1 -sother
    
                   A relative time specification may not use  AM/PM  format.   The
                   third form removes item n from the event list:
    
                       > sched
                            1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
                            2   Wed Apr  4 17:00  set prompt=[%h] It's after 5; go
                       home: >
                       > sched -2
                       > sched
                            1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
    
                   A command in the scheduled-event list is executed  just  before
                   the  first prompt is printed after the time when the command is
                   scheduled.  It is possible to miss the exact time when the com-
                   mand  is  to be run, but an overdue command will execute at the
                   next prompt.  A command which comes  due  while  the  shell  is
                   waiting  for user input is executed immediately.  However, nor-
                   mal operation of an already-running command will not be  inter-
                   rupted so that a scheduled-event list element may be run.
    
                   This  mechanism  is  similar to, but not the same as, the at(1)
                   command on some Unix systems.  Its major disadvantage  is  that
                   it  may  not  run a command at exactly the specified time.  Its
                   major advantage is that because sched runs  directly  from  the
                   shell,  it  has access to shell variables and other structures.
                   This provides a mechanism for changing one's  working  environ-
                   ment based on the time of day.
    
           set
           set name ...
           set name=word ...
           set [-r] [-f|-l] name=(wordlist) ... (+)
           set name[index]=word ...
           set -r (+)
           set -r name ... (+)
           set -r name=word ... (+)
                   The  first  form  of  the command prints the value of all shell
                   variables.  Variables which contain more  than  a  single  word
                   print  as a parenthesized word list.  The second form sets name
                   to the null string.  The third form sets  name  to  the  single
                   word.   The  fourth  form  sets  name  to  the list of words in
                   wordlist.  In all cases  the  value  is  command  and  filename
                   expanded.   If -r is specified, the value is set read-only.  If
                   -f or -l are specified, set only  unique  words  keeping  their
                   builtin command.
    
           setenv [name [value]]
                   Without  arguments, prints the names and values of all environ-
                   ment variables.  Given name, sets the environment variable name
                   to value or, without value, to the null string.
    
           setpath path (+)
                   Equivalent to setpath(1).  (Mach only)
    
           setspath LOCAL|site|cpu ... (+)
                   Sets the system execution path.  (TCF only)
    
           settc cap value (+)
                   Tells the shell to believe that the terminal capability cap (as
                   defined in termcap(5)) has the value value.  No sanity checking
                   is  done.   Concept terminal users may have to 'settc xn no' to
                   get proper wrapping at the rightmost column.
    
           setty [-d|-q|-x] [-a] [[+|-]mode] (+)
                   Controls which tty modes (see Terminal  management)  the  shell
                   does  not  allow to change.  -d, -q or -x tells setty to act on
                   the 'edit', 'quote' or 'execute' set of tty modes respectively;
                   without -d, -q or -x, 'execute' is used.
    
                   Without  other  arguments,  setty lists the modes in the chosen
                   set which are fixed on ('+mode') or off ('-mode').  The  avail-
                   able  modes,  and thus the display, vary from system to system.
                   With -a, lists all tty modes in the chosen set whether  or  not
                   they  are  fixed.   With +mode, -mode or mode, fixes mode on or
                   off or removes control from mode in the chosen set.  For  exam-
                   ple, 'setty +echok echoe' fixes 'echok' mode on and allows com-
                   mands to turn 'echoe' mode on or off, both when  the  shell  is
                   executing commands.
    
           setxvers [string] (+)
                   Set the experimental version prefix to string, or removes it if
                   string is omitted.  (TCF only)
    
           shift [variable]
                   Without arguments, discards argv[1] and shifts the  members  of
                   argv  to the left.  It is an error for argv not to be set or to
                   have less than one word as value.  With variable, performs  the
                   same function on variable.
    
           source [-h] name [args ...]
                   The  shell reads and executes commands from name.  The commands
                   are not placed on the history list.  If  any  args  are  given,
                   they are placed in argv.  (+) source commands may be nested; if
                   they are nested too deeply  the  shell  may  run  out  of  file
                   descriptors.   An error in a source at any level terminates all
                   nested source commands.  With -h, commands are  placed  on  the
    
               ...
               breaksw
           ...
           default:
               ...
               breaksw
           endsw   Each  case label is successively matched, against the specified
                   string which is first command and filename expanded.  The  file
                   metacharacters  '*',  '?'  and '[...]'  may be used in the case
                   labels, which are variable expanded.  If  none  of  the  labels
                   match  before  a  'default'  label is found, then the execution
                   begins after the  default  label.   Each  case  label  and  the
                   default label must appear at the beginning of a line.  The com-
                   mand breaksw causes execution  to  continue  after  the  endsw.
                   Otherwise  control  may  fall  through  case labels and default
                   labels as in C.  If no label matches and there is  no  default,
                   execution continues after the endsw.
    
           telltc (+)
                   Lists the values of all terminal capabilities (see termcap(5)).
    
           termname [terminal type] (+)
                   Tests if terminal type (or the current value of TERM if no ter-
                   minal  type  is  given) has an entry in the hosts termcap(5) or
                   terminfo(5) database. Prints the terminal type  to  stdout  and
                   returns 0 if an entry is present otherwise returns 1.
    
           time [command]
                   Executes command (which must be a simple command, not an alias,
                   a pipeline, a command list or a parenthesized command list) and
                   prints a time summary as described under the time variable.  If
                   necessary, an extra shell is created to print the time  statis-
                   tic when the command completes.  Without command, prints a time
                   summary for the current shell and its children.
    
           umask [value]
                   Sets the file creation mask to value, which is given in  octal.
                   Common  values  for  the mask are 002, giving all access to the
                   group and read and execute access to others,  and  022,  giving
                   read  and  execute  access  to  the  group and others.  Without
                   value, prints the current file creation mask.
    
           unalias pattern
                   Removes all aliases whose names  match  pattern.   'unalias  *'
                   thus removes all aliases.  It is not an error for nothing to be
                   unaliased.
    
           uncomplete pattern (+)
                   Removes all completions whose names match pattern.  'uncomplete
                   *'  thus removes all completions.  It is not an error for noth-
                   ing to be uncompleted.
    
           unset pattern
                   Removes all variables whose names match  pattern,  unless  they
                   are  read-only.   'unset  *'  thus removes all variables unless
                   they are read-only; this is a bad idea.  It is not an error for
                   nothing to be unset.
    
           unsetenv pattern
                   Removes  all  environment  variables whose names match pattern.
                   'unsetenv *' thus removes all environment variables; this is  a
                   bad idea.  It is not an error for nothing to be unsetenved.
    
           ver [systype [command]] (+)
                   Without  arguments, prints SYSTYPE.  With systype, sets SYSTYPE
                   to systype.  With systype and command, executes  command  under
                   systype.   systype  may  be  'bsd4.3'  or 'sys5.3'.  (Domain/OS
                   only)
    
           wait    The shell waits for all  background  jobs.   If  the  shell  is
                   interactive,  an  interrupt will disrupt the wait and cause the
                   shell to print the names and job  numbers  of  all  outstanding
                   jobs.
    
           warp universe (+)
                   Sets the universe to universe.  (Convex/OS only)
    
           watchlog (+)
                   An  alternate  name for the log builtin command (q.v.).  Avail-
                   able only if the shell was so compiled; see the  version  shell
                   variable.
    
           where command (+)
                   Reports  all  known  instances  of  command, including aliases,
                   builtins and executables in path.
    
           which command (+)
                   Displays the command that will be executed by the  shell  after
                   substitutions,  path  searching,  etc.   The builtin command is
                   just like which(1), but it correctly reports tcsh  aliases  and
                   builtins  and  is  10 to 100 times faster.  See also the which-
                   command editor command.
    
           while (expr)
           ...
           end     Executes the commands between the while and  the  matching  end
                   while  expr  (an  expression,  as  described under Expressions)
                   evaluates non-zero.  while and end must appear alone  on  their
                   input  lines.   break  and continue may be used to terminate or
                   continue the loop prematurely.  If the input is a terminal, the
                   user  is prompted the first time through the loop as with fore-
                   ach.
    
       Special aliases (+)
                   directory.  A fancier way to do that is
    
                       >          alias          cwdcmd          'echo          -n
                       "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'
    
                   This  will  put the hostname and working directory on the title
                   bar but only the hostname in the icon manager menu.
    
                   Note that putting a cd, pushd or popd in cwdcmd  may  cause  an
                   infinite loop.  It is the author's opinion that anyone doing so
                   will get what they deserve.
    
           jobcmd  Runs before each command gets executed,  or  when  the  command
                   changes  state.   This  is  similar to postcmd, but it does not
                   print builtins.
    
                       > alias jobcmd  'echo -n "^[]2\;\!#:q^G"'
    
                   then executing vi foo.c will put  the  command  string  in  the
                   xterm title bar.
    
           helpcommand
                   Invoked  by  the run-help editor command.  The command name for
                   which help is sought is passed as sole argument.  For  example,
                   if one does
    
                       > alias helpcommand '\!:1 --help'
    
                   then  the  help  display of the command itself will be invoked,
                   using the GNU help calling convention.  Currently there  is  no
                   easy  way to account for various calling conventions (e.g., the
                   customary Unix '-h'), except by using a table of many commands.
    
           periodic
                   Runs  every  tperiod minutes.  This provides a convenient means
                   for checking on common but infrequent changes such as new mail.
                   For example, if one does
    
                       > set tperiod = 30
                       > alias periodic checknews
    
                   then  the checknews(1) program runs every 30 minutes.  If peri-
                   odic is set but tperiod is unset or set to 0, periodic  behaves
                   like precmd.
    
           precmd  Runs  just  before each prompt is printed.  For example, if one
                   does
    
                       > alias precmd date
    
                   then date(1) runs just before the shell prompts for  each  com-
                   mand.  There are no limits on what precmd can be set to do, but
    
       Special shell variables
           The variables described in this section have  special  meaning  to  the
           shell.
    
           The  shell  sets  addsuffix,  argv,  autologout,  csubstnonl,  command,
           echo_style,  edit,  gid,  group,  home,  loginsh,  oid,  path,  prompt,
           prompt2,  prompt3, shell, shlvl, tcsh, term, tty, uid, user and version
           at startup; they do not change thereafter unless changed by  the  user.
           The  shell  updates  cwd,  dirstack, owd and status when necessary, and
           sets logout on logout.
    
           The shell synchronizes group, home, path, shlvl, term and user with the
           environment variables of the same names: whenever the environment vari-
           able changes the shell changes  the  corresponding  shell  variable  to
           match  (unless  the  shell variable is read-only) and vice versa.  Note
           that although cwd and PWD have identical meanings, they  are  not  syn-
           chronized  in  this  manner, and that the shell automatically intercon-
           verts the different formats of path and PATH.
    
           addsuffix (+)
                   If set, filename completion adds '/' to the end of  directories
                   and  a  space  to the end of normal files when they are matched
                   exactly.  Set by default.
    
           afsuser (+)
                   If set, autologout's autolock feature uses its value instead of
                   the local username for kerberos authentication.
    
           ampm (+)
                   If set, all times are shown in 12-hour AM/PM format.
    
           anyerror (+)
                   This  variable  selects  what is propagated to the value of the
                   status variable. For more information see  the  description  of
                   the status variable below.
    
           argv    The  arguments  to  the shell.  Positional parameters are taken
                   from argv, i.e., '$1' is replaced by '$argv[1]', etc.   Set  by
                   default, but usually empty in interactive shells.
    
           autocorrect (+)
                   If  set, the spell-word editor command is invoked automatically
                   before each completion attempt.
    
           autoexpand (+)
                   If set, the expand-history editor command is invoked  automati-
                   cally  before  each completion attempt. If this is set to only-
                   history, then only history will be expanded and a  second  com-
                   pletion will expand filenames.
    
           autolist (+)
                   If set, possibilities are listed after an ambiguous completion.
                   DISPLAY  environment  variable is set), the tty is a pseudo-tty
                   (pty) or the shell was not so compiled (see the  version  shell
                   variable).  See also the afsuser and logout shell variables.
    
           backslash_quote (+)
                   If set, backslashes ('\') always quote '\', ''', and '"'.  This
                   may make complex quoting tasks easier, but it can cause  syntax
                   errors in csh(1) scripts.
    
           catalog The  file  name  of  the  message  catalog.   If  set, tcsh use
                   'tcsh.${catalog}' as  a  message  catalog  instead  of  default
                   'tcsh'.
    
           cdpath  A list of directories in which cd should search for subdirecto-
                   ries if they aren't found in the current directory.
    
           color   If set, it enables color display for the builtin  ls-F  and  it
                   passes  --color=auto  to  ls.   Alternatively, it can be set to
                   only ls-F or only ls to enable color to only one command.  Set-
                   ting it to nothing is equivalent to setting it to (ls-F ls).
    
           colorcat
                   If set, it enables color escape sequence for NLS message files.
                   And display colorful NLS messages.
    
           command (+)
                   If set, the command which was passed to the shell with  the  -c
                   flag (q.v.).
    
           compat_expr (+)
                   If set, the shell will evaluate expressions right to left, like
                   the original csh.
    
           complete (+)
                   If set to 'enhance', completion 1) ignores case and 2)  consid-
                   ers  periods,  hyphens and underscores ('.', '-' and '_') to be
                   word separators and hyphens and underscores to  be  equivalent.
                   If set to 'igncase', the completion becomes case insensitive.
    
           continue (+)
                   If  set  to  a  list  of  commands, the shell will continue the
                   listed commands, instead of starting a new one.
    
           continue_args (+)
                   Same as continue, but the shell will execute:
    
                       echo 'pwd' $argv > ~/.<cmd>_pause; %<cmd>
    
           correct (+)
                   If set to 'cmd', commands are automatically spelling-corrected.
                   If set to 'complete', commands are automatically completed.  If
                   set to 'all', the entire command line is corrected.
                   a history file.  If unset, ~/.cshdirs is  used.   Because  only
                   ~/.tcshrc  is  normally  sourced  before  ~/.cshdirs,  dirsfile
                   should be set in ~/.tcshrc rather than ~/.login.
    
           dirstack (+)
                   An array  of  all  the  directories  on  the  directory  stack.
                   '$dirstack[1]' is the current working directory, '$dirstack[2]'
                   the first directory on the stack, etc.  Note that  the  current
                   working directory is '$dirstack[1]' but '=0' in directory stack
                   substitutions, etc.  One can change the  stack  arbitrarily  by
                   setting  dirstack,  but  the first element (the current working
                   directory) is always correct.  See also the cwd and  owd  shell
                   variables.
    
           dspmbyte (+)
                   Has an affect iff 'dspm' is listed as part of the version shell
                   variable.  If set to 'euc', it enables display and editing EUC-
                   kanji(Japanese) code.  If set to 'sjis', it enables display and
                   editing Shift-JIS(Japanese) code.  If set to 'big5', it enables
                   display  and  editing Big5(Chinese) code.  If set to 'utf8', it
                   enables display and editing Utf8(Unicode) code.  If set to  the
                   following  format,  it  enables display and editing of original
                   multi-byte code format:
    
                       > set dspmbyte = 0000....(256 bytes)....0000
    
                   The table requires just 256 bytes.  Each character of 256 char-
                   acters  corresponds  (from  left  to  right) to the ASCII codes
                   0x00, 0x01, ... 0xff.  Each character is set  to  number  0,1,2
                   and 3.  Each number has the following meaning:
                     0 ... not used for multi-byte characters.
                     1 ... used for the first byte of a multi-byte character.
                     2 ... used for the second byte of a multi-byte character.
                     3  ...  used  for  both  the  first byte and second byte of a
                   multi-byte character.
    
                     Example:
                   If set to '001322', the first  character  (means  0x00  of  the
                   ASCII code) and second character (means 0x01 of ASCII code) are
                   set to '0'.  Then, it is not used  for  multi-byte  characters.
                   The  3rd  character (0x02) is set to '1', indicating that it is
                   used for the first byte of a  multi-byte  character.   The  4th
                   character(0x03) is set '3'.  It is used for both the first byte
                   and the second byte of a multi-byte character.  The 5th and 6th
                   characters (0x04,0x05) are set to '2', indicating that they are
                   used for the second byte of a multi-byte character.
    
           echo    If  set,  each command with its arguments is echoed just before
                   it is executed.  For non-builtin commands all expansions  occur
                   before echoing.  Builtin commands are echoed before command and
                   filename substitution, because  these  substitutions  are  then
                   done selectively.  Set by the -x command line option.
    
           echo_style (+)
                   The style of the echo builtin.  May be set to
    
                   bsd     Don't echo a newline if the first argument is '-n'.
                   sysv    Recognize backslashed escape sequences in echo strings.
                   both    Recognize both the '-n'  flag  and  backslashed  escape
                           sequences; the default.
                   none    Recognize neither.
    
                   Set by default to the local system default.  The BSD and System
                   V options are described in the echo(1) man pages on the  appro-
                   priate systems.
    
           edit (+)
                   If  set,  the  command-line  editor is used.  Set by default in
                   interactive shells.
    
           ellipsis (+)
                   If set, the '%c'/'%.' and '%C' prompt sequences (see the prompt
                   shell  variable)  indicate skipped directories with an ellipsis
                   ('...')  instead of '/<skipped>'.
    
           fignore (+)
                   Lists file name suffixes to be ignored by completion.
    
           filec   In tcsh, completion is always used and this variable is ignored
                   by  default.  If  edit  is  unset,  then  the  traditional  csh
                   completion is used.  If set  in  csh,  filename  completion  is
                   used.
    
           gid (+) The user's real group ID.
    
           group (+)
                   The user's group name.
    
           highlight
                   If  set,  the incremental search match (in i-search-back and i-
                   search-fwd) and the region between the mark and the cursor  are
                   highlighted in reverse video.
    
                   Highlighting  requires  more  frequent  terminal  writes, which
                   introduces extra overhead. If you care about  terminal  perfor-
                   mance, you may want to leave this unset.
    
           histchars
                   A  string value determining the characters used in History sub-
    
           histfile (+)
                   The default location in which 'history  -S'  and  'history  -L'
                   look  for a history file.  If unset, ~/.history is used.  hist-
                   file is useful when sharing the  same  home  directory  between
                   different  machines,  or when saving separate histories on dif-
                   ferent terminals.  Because only ~/.tcshrc is  normally  sourced
                   before  ~/.history,  histfile should be set in ~/.tcshrc rather
                   than ~/.login.
    
           histlit (+)
                   If set, builtin and editor commands and the savehist  mechanism
                   use the literal (unexpanded) form of lines in the history list.
                   See also the toggle-literal-history editor command.
    
           history The first word indicates the number of history events to  save.
                   The optional second word (+) indicates the format in which his-
                   tory is printed; if not given,  '%h\t%T\t%R\n'  is  used.   The
                   format  sequences  are  described  below under prompt; note the
                   variable meaning of '%R'.  Set to '100' by default.
    
           home    Initialized to the home directory of the invoker.  The filename
                   expansion of '~' refers to this variable.
    
           ignoreeof
                   If  set  to  the  empty string or '0' and the input device is a
                   terminal, the end-of-file command  (usually  generated  by  the
                   user by typing '^D' on an empty line) causes the shell to print
                   'Use "exit" to leave tcsh.' instead of exiting.  This  prevents
                   the  shell  from  accidentally being killed.  Historically this
                   setting exited after 26  successive  EOF's  to  avoid  infinite
                   loops.   If set to a number n, the shell ignores n - 1 consecu-
                   tive end-of-files and exits on the nth.  (+) If unset,  '1'  is
                   used, i.e., the shell exits on a single '^D'.
    
           implicitcd (+)
                   If set, the shell treats a directory name typed as a command as
                   though it were a request to change to that directory.   If  set
                   to  verbose,  the change of directory is echoed to the standard
                   output.  This behavior is inhibited  in  non-interactive  shell
                   scripts,  or  for  command  strings  with  more  than one word.
                   Changing directory takes precedence over executing a like-named
                   command,  but  it is done after alias substitutions.  Tilde and
                   variable expansions work as expected.
    
           inputmode (+)
                   If set to 'insert' or 'overwrite', puts the  editor  into  that
                   input mode at the beginning of each line.
    
           killdup (+)
                   Controls  handling  of  duplicate entries in the kill ring.  If
                   set to 'all' only unique strings are entered in the kill  ring.
                   command-line, while yank-pop (see Editor commands) can be  used
                   to yank earlier killed strings.
    
           listflags (+)
                   If  set  to  'x', 'a' or 'A', or any combination thereof (e.g.,
                   'xA'), they are used as flags to ls-F, making it act  like  'ls
                   -xF',  'ls  -Fa',  'ls -FA' or a combination (e.g., 'ls -FxA'):
                   'a' shows all files (even if they start with a '.'), 'A'  shows
                   all  files  but  '.'  and '..', and 'x' sorts across instead of
                   down.  If the second word of listflags is set, it  is  used  as
                   the path to 'ls(1)'.
    
           listjobs (+)
                   If set, all jobs are listed when a job is suspended.  If set to
                   'long', the listing is in long format.
    
           listlinks (+)
                   If set, the ls-F builtin command shows  the  type  of  file  to
                   which each symbolic link points.
    
           listmax (+)
                   The  maximum number of items which the list-choices editor com-
                   mand will list without asking first.
    
           listmaxrows (+)
                   The maximum number of rows of items which the list-choices edi-
                   tor command will list without asking first.
    
           loginsh (+)
                   Set  by the shell if it is a login shell.  Setting or unsetting
                   it within a shell has no effect.  See also shlvl.
    
           logout (+)
                   Set by the shell to 'normal' before  a  normal  logout,  'auto-
                   matic'  before  an  automatic logout, and 'hangup' if the shell
                   was killed by a hangup signal (see Signal handling).  See  also
                   the autologout shell variable.
    
           mail    The  names  of  the  files or directories to check for incoming
                   mail, separated by whitespace, and  optionally  preceded  by  a
                   numeric  word.   Before  each prompt, if 10 minutes have passed
                   since the last check, the shell checks each file and says  'You
                   have new mail.' (or, if mail contains multiple files, 'You have
                   new mail in name.') if the filesize is  greater  than  zero  in
                   size  and has a modification time greater than its access time.
    
                   If you are in a login shell, then  no  mail  file  is  reported
                   unless  it  has  been  modified  after  the  time the shell has
                   started up, to prevent  redundant  notifications.   Most  login
                   programs  will  tell  you whether or not you have mail when you
                   log in.
    
           matchbeep (+)
                   If   set  to  'never',  completion  never  beeps.   If  set  to
                   'nomatch', it beeps only when there is no  match.   If  set  to
                   'ambiguous',  it beeps when there are multiple matches.  If set
                   to 'notunique', it beeps when there  is  one  exact  and  other
                   longer matches.  If unset, 'ambiguous' is used.
    
           nobeep (+)
                   If  set, beeping is completely disabled.  See also visiblebell.
    
           noclobber
                   If set, restrictions are placed on output redirection to insure
                   that  files  are  not  accidentally  destroyed  and  that  '>>'
                   redirections refer to  existing  files,  as  described  in  the
                   Input/output section.
    
           noding  If  set,  disable  the  printing  of 'DING!' in the prompt time
                   specifiers at the change of hour.
    
           noglob  If set, Filename substitution and Directory stack  substitution
                   (q.v.)  are  inhibited.   This  is most useful in shell scripts
                   which do not deal with filenames, or after a list of  filenames
                   has been obtained and further expansions are not desirable.
    
           nokanji (+)
                   If  set  and  the  shell  supports Kanji (see the version shell
                   variable), it is disabled so that the meta key can be used.
    
           nonomatch
                   If set, a Filename substitution or Directory stack substitution
                   (q.v.)  which  does  not  match  any  existing  files  is  left
                   untouched rather than causing an error.  It is still  an  error
                   for  the  substitution  to  be  malformed, e.g., 'echo [' still
                   gives an error.
    
           nostat (+)
                   A list of directories (or glob-patterns  which  match  directo-
                   ries;  see  Filename substitution) that should not be stat(2)ed
                   during a completion operation.  This is usually used to exclude
                   directories  which  take  too much time to stat(2), for example
                   /afs.
    
           notify  If set, the shell  announces  job  completions  asynchronously.
                   The  default is to present job completions just before printing
                   a prompt.
    
           oid (+) The user's real organization ID.  (Domain/OS only)
    
           owd (+) The old working directory, equivalent to the '-' used by cd and
                   pushd.  See also the cwd and dirstack shell variables.
    
           padhour If set, enable the printing of padding '0' for hours, in 24 and
                   need to do a rehash for the shell to find it.
    
           printexitvalue (+)
                   If set and an interactive program exits with a non-zero status,
                   the shell prints 'Exit status'.
    
           prompt  The  string  which  is printed before reading each command from
                   the terminal.  prompt may include any of the following  format-
                   ting  sequences  (+),  which are replaced by the given informa-
                   tion:
    
                   %/  The current working directory.
                   %~  The current working directory, but with one's  home  direc-
                       tory  represented  by '~' and other users' home directories
                       represented  by  '~user'  as  per  Filename   substitution.
                       '~user'  substitution happens only if the shell has already
                       used '~user' in a pathname in the current session.
                   %c[[0]n], %.[[0]n]
                       The trailing component of the current working directory, or
                       n  trailing  components if a digit n is given.  If n begins
                       with '0', the number  of  skipped  components  precede  the
                       trailing  component(s)  in the format '/<skipped>trailing'.
                       If the ellipsis shell variable is set,  skipped  components
                       are  represented  by  an  ellipsis  so  the  whole  becomes
                       '...trailing'.  '~' substitution is done as in '%~'  above,
                       but  the  '~'  component  is ignored when counting trailing
                       components.
                   %C  Like %c, but without '~' substitution.
                   %h, %!, !
                       The current history event number.
                   %M  The full hostname.
                   %m  The hostname up to the first '.'.
                   %S (%s)
                       Start (stop) standout mode.
                   %B (%b)
                       Start (stop) boldfacing mode.
                   %U (%u)
                       Start (stop) underline mode.
                   %t, %@
                       The time of day in 12-hour AM/PM format.
                   %T  Like '%t', but in 24-hour format (but see  the  ampm  shell
                       variable).
                   %p  The  'precise'  time  of  day in 12-hour AM/PM format, with
                       seconds.
                   %P  Like '%p', but in 24-hour format (but see  the  ampm  shell
                       variable).
                   \c  c is parsed as in bindkey.
                   ^c  c is parsed as in bindkey.
                   %%  A single '%'.
                   %n  The user name.
                   %j  The number of jobs.
                   %d  The weekday in 'Day' format.
                       Includes string as a literal escape sequence.  It should be
                       used only to change terminal attributes and should not move
                       the  cursor  location.  This cannot be the last sequence in
                       prompt.
                   %?  The return code of the command  executed  just  before  the
                       prompt.
                   %R  In prompt2, the status of the parser.  In prompt3, the cor-
                       rected string.  In history, the history string.
    
                   '%B', '%S', '%U' and '%{string%}' are available in only  eight-
                   bit-clean shells; see the version shell variable.
    
                   The  bold,  standout  and underline sequences are often used to
                   distinguish a superuser shell.  For example,
    
                       > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
                       tut [37] [2:54pm] [/usr/accts/sys] you rang? _
    
                   If '%t', '%@', '%T', '%p', or '%P' is used, and noding  is  not
                   set,  then print 'DING!' on the change of hour (i.e, ':00' min-
                   utes) instead of the actual time.
    
                   Set by default to '%# ' in interactive shells.
    
           prompt2 (+)
                   The string with which to prompt in while and foreach loops  and
                   after  lines  ending  in '\'.  The same format sequences may be
                   used as in prompt (q.v.); note the variable  meaning  of  '%R'.
                   Set by default to '%R? ' in interactive shells.
    
           prompt3 (+)
                   The  string  with  which  to  prompt  when confirming automatic
                   spelling correction.  The same format sequences may be used  as
                   in  prompt  (q.v.);  note the variable meaning of '%R'.  Set by
                   default to 'CORRECT>%R (y|n|e|a)? ' in interactive shells.
    
           promptchars (+)
                   If  set  (to  a  two-character  string),  the  '%#'  formatting
                   sequence  in  the  prompt  shell  variable is replaced with the
                   first character for normal users and the second  character  for
                   the superuser.
    
           pushdtohome (+)
                   If set, pushd without arguments does 'pushd ~', like cd.
    
           pushdsilent (+)
                   If set, pushd and popd do not print the directory stack.
    
           recexact (+)
                   If set, completion completes on an exact match even if a longer
                   match is possible.
    
                   the  first  line.   If  edit  isn't  set,  then rprompt will be
                   printed after the prompt and before the command input.
    
           savedirs (+)
                   If set, the shell does 'dirs -S' before exiting.  If the  first
                   word  is  set  to  a  number, at most that many directory stack
                   entries are saved.
    
           savehist
                   If set, the shell does 'history -S'  before  exiting.   If  the
                   first  word  is  set  to  a number, at most that many lines are
                   saved.  (The number must be less than or equal to history.)  If
                   the  second  word is set to 'merge', the history list is merged
                   with the existing history file  instead  of  replacing  it  (if
                   there  is  one)  and  sorted  by time stamp and the most recent
                   events are retained.  (+)
    
           sched (+)
                   The format in which the sched builtin command prints  scheduled
                   events;  if  not  given,  '%h\t%T\t%R\n'  is  used.  The format
                   sequences are described above under prompt; note  the  variable
                   meaning of '%R'.
    
           shell   The  file  in which the shell resides.  This is used in forking
                   shells to interpret files which  have  execute  bits  set,  but
                   which  are  not executable by the system.  (See the description
                   of Builtin and non-builtin command execution.)  Initialized  to
                   the (system-dependent) home of the shell.
    
           shlvl (+)
                   The  number of nested shells.  Reset to 1 in login shells.  See
                   also loginsh.
    
           status  The exit status from the last command or  backquote  expansion,
                   or any command in a pipeline is propagated to status.  (This is
                   also the default csh behavior.)  This default  does  not  match
                   what  POSIX  mandates (to return the status of the last command
                   only). To match the POSIX behavior, you need to unset anyerror.
    
                   If  the  anyerror  variable  is  unset,  the  exit  status of a
                   pipeline is determined  only  from  the  last  command  in  the
                   pipeline,  and  the exit status of a backquote expansion is not
                   propagated to status.
    
                   If a command terminated abnormally, then 0200 is added  to  the
                   status.   Builtin  commands  which fail return exit status '1',
                   all other builtin commands return status '0'.
    
           symlinks (+)
                   Can be set to several different values to control symbolic link
                   ('symlink') resolution:
    
                   does  not  work  for hard-to-recognize filenames, such as those
                   embedded in command options.  Expansion  may  be  prevented  by
                   quoting.  While this setting is usually the most convenient, it
                   is sometimes misleading and sometimes confusing when  it  fails
                   to  recognize  an argument which should be expanded.  A compro-
                   mise is to use 'ignore' and use the editor  command  normalize-
                   path (bound by default to ^X-n) when necessary.
    
                   Some  examples  are  in  order.   First, let's set up some play
                   directories:
    
                       > cd /tmp
                       > mkdir from from/src to
                       > ln -s from/src to/dst
    
                   Here's the behavior with symlinks unset,
    
                       > cd /tmp/to/dst; echo $cwd
                       /tmp/to/dst
                       > cd ..; echo $cwd
                       /tmp/from
    
                   here's the behavior with symlinks set to 'chase',
    
                       > cd /tmp/to/dst; echo $cwd
                       /tmp/from/src
                       > cd ..; echo $cwd
                       /tmp/from
    
                   here's the behavior with symlinks set to 'ignore',
    
                       > cd /tmp/to/dst; echo $cwd
                       /tmp/to/dst
                       > cd ..; echo $cwd
                       /tmp/to
    
                   and here's the behavior with symlinks set to 'expand'.
    
                       > cd /tmp/to/dst; echo $cwd
                       /tmp/to/dst
                       > cd ..; echo $cwd
                       /tmp/to
                       > cd /tmp/to/dst; echo $cwd
                       /tmp/to/dst
                       > cd ".."; echo $cwd
                       /tmp/from
                       > /bin/echo ..
                       /tmp/to
                       > /bin/echo ".."
                       ..
    
                   Note that 'expand' expansion 1) works just  like  'ignore'  for
                   string for the output of the time builtin.  (u)  The  following
                   sequences may be used in the format string:
    
                   %U  The time the process spent in user mode in cpu seconds.
                   %S  The time the process spent in kernel mode in cpu seconds.
                   %E  The elapsed (wall clock) time in seconds.
                   %P  The CPU percentage computed as (%U + %S) / %E.
                   %W  Number of times the process was swapped.
                   %X  The average amount in (shared) text space used in Kbytes.
                   %D  The  average  amount in (unshared) data/stack space used in
                       Kbytes.
                   %K  The total space used (%X + %D) in Kbytes.
                   %M  The maximum memory the process had in use at  any  time  in
                       Kbytes.
                   %F  The  number of major page faults (page needed to be brought
                       from disk).
                   %R  The number of minor page faults.
                   %I  The number of input operations.
                   %O  The number of output operations.
                   %r  The number of socket messages received.
                   %s  The number of socket messages sent.
                   %k  The number of signals received.
                   %w  The number of voluntary context switches (waits).
                   %c  The number of involuntary context switches.
    
                   Only the first four sequences are supported on systems  without
                   BSD  resource limit functions.  The default time format is '%Uu
                   %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww'  for  systems  that  support
                   resource  usage  reporting and '%Uu %Ss %E %P' for systems that
                   do not.
    
                   Under Sequent's DYNIX/ptx, %X, %D, %K, %r and %s are not avail-
                   able, but the following additional sequences are:
    
                   %Y  The number of system calls performed.
                   %Z  The number of pages which are zero-filled on demand.
                   %i  The  number  of  times  a  process's  resident set size was
                       increased by the kernel.
                   %d  The number of times  a  process's  resident  set  size  was
                       decreased by the kernel.
                   %l  The number of read system calls performed.
                   %m  The number of write system calls performed.
                   %p  The number of reads from raw disk devices.
                   %q  The number of writes to raw disk devices.
    
                   and  the  default  time  format  is  '%Uu  %Ss  %E  %P  %I+%Oio
                   %Fpf+%Ww'.  Note that the CPU percentage  can  be  higher  than
                   100% on multi-processors.
    
           tperiod (+)
                   The period, in minutes, between executions of the periodic spe-
                   cial alias.
                   machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-separated
                   list  of options which were set at compile time.  Options which
                   are set by default in the distribution are noted.
    
                   8b    The shell is eight bit clean; default
                   7b    The shell is not eight bit clean
                   wide  The shell is multibyte encoding clean (like UTF-8)
                   nls   The system's NLS is used; default for systems with NLS
                   lf    Login shells execute  /etc/csh.login  before  instead  of
                         after /etc/csh.cshrc and ~/.login before instead of after
                         ~/.tcshrc and ~/.history.
                   dl    '.' is put last in path for security; default
                   nd    '.' is omitted from path for security
                   vi    vi-style editing is the default rather than emacs
                   dtr   Login shells drop DTR when exiting
                   bye   bye is a synonym for logout and log is an alternate  name
                         for watchlog
                   al    autologout is enabled; default
                   kan   Kanji  is  used  if  appropriate according to locale set-
                         tings, unless the nokanji shell variable is set
                   sm    The system's malloc(3) is used
                   hb    The '#!<program> <args>' convention is emulated when exe-
                         cuting shell scripts
                   ng    The newgrp builtin is available
                   rh    The  shell  attempts  to  set  the REMOTEHOST environment
                         variable
                   afs   The shell verifies your password with the kerberos server
                         if  local  authentication fails.  The afsuser shell vari-
                         able or the AFSUSER environment  variable  override  your
                         local username if set.
    
                   An  administrator may enter additional strings to indicate dif-
                   ferences in the local version.
    
           visiblebell (+)
                   If set, a screen flash is used rather than  the  audible  bell.
                   See also nobeep.
    
           watch (+)
                   A  list of user/terminal pairs to watch for logins and logouts.
                   If either the user is 'any' all terminals are watched  for  the
                   given  user  and  vice  versa.   Setting  watch  to '(any any)'
                   watches all users and terminals.  For example,
    
                       set watch = (george ttyd1 any console $user any)
    
                   reports activity of the user 'george' on ttyd1, any user on the
                   console, and oneself (or a trespasser) on any terminal.
    
                   Logins and logouts are checked every 10 minutes by default, but
                   the first word of watch can be set to a number to  check  every
                   so many minutes.  For example,
                   %a  The  observed  action,  i.e.,  'logged on', 'logged off' or
                       'replaced olduser on'.
                   %l  The terminal (tty) on which the user logged in/out.
                   %M  The full hostname of the remote host,  or  'local'  if  the
                       login/logout was from the local host.
                   %m  The  hostname  of the remote host up to the first '.'.  The
                       full name is printed if it is an IP address or an X  Window
                       System display.
    
                   %M  and  %m are available on only systems that store the remote
                   hostname in /etc/utmp.  If unset, '%n has %a %l  from  %m.'  is
                   used,  or  '%n  has  %a  %l.'  on systems which don't store the
                   remote hostname.
    
           wordchars (+)
                   A list of non-alphanumeric characters to be considered part  of
                   a  word  by  the  forward-word, backward-word etc., editor com-
                   mands.  If unset, '*?_-.[]~=' is used.
    
    
    

    ENVIRONMENT

           AFSUSER (+)
                   Equivalent to the afsuser shell variable.
    
           COLUMNS The number of columns in the terminal.   See  Terminal  manage-
                   ment.
    
           DISPLAY Used by X Window System (see X(1)).  If set, the shell does not
                   set autologout (q.v.).
    
           EDITOR  The pathname to a default editor.  See also the VISUAL environ-
                   ment variable and the run-fg-editor editor command.
    
           GROUP (+)
                   Equivalent to the group shell variable.
    
           HOME    Equivalent to the home shell variable.
    
           HOST (+)
                   Initialized  to  the  name of the machine on which the shell is
                   running, as determined by the gethostname(2) system call.
    
           HOSTTYPE (+)
                   Initialized to the type of machine on which the shell  is  run-
                   ning, as determined at compile time.  This variable is obsolete
                   and will be removed in a future version.
    
           HPATH (+)
                   A colon-separated list of directories  in  which  the  run-help
                   editor command looks for command documentation.
    
           LANG    Gives the preferred character environment.  See Native Language
                   System support.
                       fi   0      Regular file
                       di   01;34  Directory
                       ln   01;36  Symbolic link
                       pi   33     Named pipe (FIFO)
                       so   01;35  Socket
                       do   01;35  Door
                       bd   01;33  Block device
                       cd   01;32  Character device
                       ex   01;32  Executable file
                       mi   (none) Missing file (defaults to fi)
                       or   (none) Orphaned symbolic link (defaults to ln)
                       lc   ^[[    Left code
                       rc   m      Right code
                       ec   (none) End code (replaces lc+no+rc)
    
                   You  need to include only the variables you want to change from
                   the default.
    
                   File names can also be colorized based on  filename  extension.
                   This  is  specified  in the LS_COLORS variable using the syntax
                   "*ext=string".  For example, using ISO 6429 codes, to color all
                   C-language  source files blue you would specify "*.c=34".  This
                   would color all files ending in .c in blue (34) color.
    
                   Control characters can be  written  either  in  C-style-escaped
                   notation,  or  in  stty-like  ^-notation.  The C-style notation
                   adds ^[ for Escape, _ for a normal space character, and  ?  for
                   Delete.   In  addition,  the ^[ escape character can be used to
                   override the default interpretation of ^[, ^, : and =.
    
                   Each file will be written as <lc> <color-code> <rc>  <filename>
                   <ec>.   If  the  <ec> code is undefined, the sequence <lc> <no>
                   <rc> will be used instead.  This is generally  more  convenient
                   to  use,  but  less general.  The left, right and end codes are
                   provided so you don't have to type common parts over  and  over
                   again  and  to  support weird terminals; you will generally not
                   need to change them at all unless your terminal  does  not  use
                   ISO 6429 color sequences but a different system.
    
                   If your terminal does use ISO 6429 color codes, you can compose
                   the type codes (i.e., all except the lc, rc, and ec codes) from
                   numerical  commands  separated  by semicolons.  The most common
                   commands are:
    
                           0   to restore default color
                           1   for brighter colors
                           4   for underlined text
                           5   for flashing text
                           30  for black foreground
                           31  for red foreground
                           32  for green foreground
                           33  for yellow (or brown) foreground
    
                   A few terminal programs do not recognize the default  end  code
                   properly.   If all text gets colorized after you do a directory
                   listing, try changing the no and fi codes from 0 to the numeri-
                   cal codes for your standard fore- and background colors.
    
           MACHTYPE (+)
                   The  machine  type  (microprocessor class or machine model), as
                   determined at compile time.
    
           NOREBIND (+)
                   If set, printable characters are not  rebound  to  self-insert-
                   command.  See Native Language System support.
    
           OSTYPE (+)
                   The operating system, as determined at compile time.
    
           PATH    A colon-separated list of directories in which to look for exe-
                   cutables.  Equivalent to the path shell variable, but in a dif-
                   ferent format.
    
           PWD (+) Equivalent  to  the cwd shell variable, but not synchronized to
                   it; updated only after an actual directory change.
    
           REMOTEHOST (+)
                   The host from which the user has logged in remotely, if this is
                   the  case  and  the shell is able to determine it.  Set only if
                   the shell was so compiled; see the version shell variable.
    
           SHLVL (+)
                   Equivalent to the shlvl shell variable.
    
           SYSTYPE (+)
                   The current system type.  (Domain/OS only)
    
           TERM    Equivalent to the term shell variable.
    
           TERMCAP The terminal capability string.  See Terminal management.
    
           USER    Equivalent to the user shell variable.
    
           VENDOR (+)
                   The vendor, as determined at compile time.
    
           VISUAL  The pathname to a default full-screen  editor.   See  also  the
                   EDITOR  environment  variable and the run-fg-editor editor com-
                   mand.
    
    
    

    FILES

           /etc/csh.cshrc  Read first by every shell.  ConvexOS, Stellix and Intel
                           use  /etc/cshrc  and  NeXTs  use /etc/cshrc.std.  A/UX,
                           AMIX, Cray and IRIX have no equivalent in  csh(1),  but
    
           ~/.login        Read by login shells  after  ~/.tcshrc  or  ~/.history.
                           The  shell  may  be  compiled  to  read ~/.login before
                           instead of after ~/.tcshrc and ~/.history; see the ver-
                           sion shell variable.
           ~/.cshdirs (+)  Read by login shells after ~/.login if savedirs is set,
                           but see also dirsfile.
           /etc/csh.logout Read by login shells at logout.  ConvexOS, Stellix  and
                           Intel  use  /etc/logout  and NeXTs use /etc/logout.std.
                           A/UX, AMIX, Cray and IRIX have no equivalent in csh(1),
                           but  read  this  file in tcsh anyway.  Solaris 2.x does
                           not have it either, but tcsh reads /etc/.logout.  (+)
           ~/.logout       Read by login shells at logout after /etc/csh.logout or
                           its equivalent.
           /bin/sh         Used  to  interpret  shell  scripts not starting with a
                           '#'.
           /tmp/sh*        Temporary file for '<<'.
           /etc/passwd     Source of home directories for '~name' substitutions.
    
           The order in which startup files are read may differ if the  shell  was
           so compiled; see Startup and shutdown and the version shell variable.
    
    
    

    NEW FEATURES (+)

           This  manual  describes tcsh as a single entity, but experienced csh(1)
           users will want to pay special attention to tcsh's new features.
    
           A command-line editor, which supports  GNU  Emacs  or  vi(1)-style  key
           bindings.  See The command-line editor and Editor commands.
    
           Programmable,  interactive word completion and listing.  See Completion
           and listing and the complete and uncomplete builtin commands.
    
           Spelling correction (q.v.) of filenames, commands and variables.
    
           Editor commands (q.v.) which perform other useful functions in the mid-
           dle of typed commands, including documentation lookup (run-help), quick
           editor restarting (run-fg-editor) and  command  resolution  (which-com-
           mand).
    
           An  enhanced  history  mechanism.  Events in the history list are time-
           stamped.  See also the history command and its associated  shell  vari-
           ables,  the  previously  undocumented '#' event specifier and new modi-
           fiers under History substitution, the *-history,  history-search-*,  i-
           search-*,  vi-search-*  and  toggle-literal-history editor commands and
           the histlit shell variable.
    
           Enhanced directory parsing and directory stack handling.  See  the  cd,
           pushd, popd and dirs commands and their associated shell variables, the
           description of Directory stack substitution, the dirstack, owd and sym-
           links shell variables and the normalize-command and normalize-path edi-
           tor commands.
    
           Negation in glob-patterns.  See Filename substitution.
           New  builtin  commands including builtins, hup, ls-F, newgrp, printenv,
           which and where (q.v.).
    
           New variables that make useful  information  easily  available  to  the
           shell.   See  the  gid, loginsh, oid, shlvl, tcsh, tty, uid and version
           shell variables and the HOST, REMOTEHOST, VENDOR, OSTYPE  and  MACHTYPE
           environment variables.
    
           A new syntax for including useful information in the prompt string (see
           prompt).  and special prompts for loops and  spelling  correction  (see
           prompt2 and prompt3).
    
           Read-only variables.  See Variable substitution.
    
    
    

    BUGS

           When  a  suspended command is restarted, the shell prints the directory
           it started in if this is different from the  current  directory.   This
           can be misleading (i.e., wrong) as the job may have changed directories
           internally.
    
           Shell  builtin  functions  are  not   stoppable/restartable.    Command
           sequences  of the form 'a ; b ; c' are also not handled gracefully when
           stopping is attempted.  If you suspend 'b', the shell will then immedi-
           ately  execute  'c'.   This  is especially noticeable if this expansion
           results from an alias.  It suffices to place the sequence  of  commands
           in ()'s to force it to a subshell, i.e., '( a ; b ; c )'.
    
           Control  over tty output after processes are started is primitive; per-
           haps this will inspire someone to  work  on  a  good  virtual  terminal
           interface.   In  a  virtual  terminal  interface  much more interesting
           things could be done with output control.
    
           Alias substitution is most often used to clumsily simulate shell proce-
           dures; shell procedures should be provided rather than aliases.
    
           Commands  within  loops  are  not  placed in the history list.  Control
           structures should be parsed rather than being  recognized  as  built-in
           commands.   This would allow control commands to be placed anywhere, to
           be combined with '|', and to be used with '&' and ';' metasyntax.
    
           foreach doesn't ignore here documents when looking for its end.
    
           It should be possible to use the ':' modifiers on the output of command
           substitutions.
    
           The  screen  update for lines longer than the screen width is very poor
           if the terminal cannot move the cursor up (i.e., terminal type 'dumb').
    
           HPATH and NOREBIND don't need to be environment variables.
    
           Glob-patterns  which  do  not use '?', '*' or '[]' or which use '{}' or
           '~' are not negated correctly.
    
    
    

    THE T IN TCSH

           In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementa-
           tion.   It  was  re-christened  the DECsystem-10 in 1970 or so when DEC
           brought out the second model, the KI10.
    
           TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts
           think  tank)  in  1972  as an experiment in demand-paged virtual memory
           operating systems.  They built a new pager for the DEC PDP-10 and  cre-
           ated the OS to go with it.  It was extremely successful in academia.
    
           In  1975,  DEC  brought  out  a new model of the PDP-10, the KL10; they
           intended to have only a version of TENEX, which they had licensed  from
           BBN,  for  the new box.  They called their version TOPS-20 (their capi-
           talization is trademarked).  A lot of  TOPS-10  users  ('The  OPerating
           System  for PDP-10') objected; thus DEC found themselves supporting two
           incompatible systems on the same hardware--but then there were 6 on the
           PDP-11!
    
           TENEX,  and  TOPS-20  to  version 3, had command completion via a user-
           code-level subroutine library called ULTCMD.  With version 3, DEC moved
           all  that  capability  and more into the monitor ('kernel' for you Unix
           types), accessed by the COMND% JSYS ('Jump to SYStem' instruction,  the
           supervisor call mechanism [are my IBM roots also showing?]).
    
           The creator of tcsh was impressed by this feature and several others of
           TENEX and TOPS-20, and created a version of csh which mimicked them.
    
    
    

    LIMITATIONS

           The system limits argument lists to ARG_MAX characters.
    
           The number of arguments to a command which involves filename  expansion
           is  limited  to  1/6th  the number of characters allowed in an argument
           list.
    
           Command substitutions  may  substitute  no  more  characters  than  are
           allowed in an argument list.
    
           To  detect  looping,  the shell restricts the number of alias substitu-
           tions on a single line to 20.
    
    
    

    SEE ALSO

           csh(1), emacs(1), ls(1), newgrp(1), sh(1), setpath(1), stty(1),  su(1),
           tset(1),   vi(1),   x(1),  access(2),  execve(2),  fork(2),  killpg(2),
           pipe(2), setrlimit(2), sigvec(2), stat(2), umask(2), vfork(2), wait(2),
           malloc(3),  setlocale(3),  tty(4),  a.out(5),  termcap(5),  environ(7),
           termio(7), Introduction to the C Shell
    
    
    

    VERSION

           This manual documents tcsh 6.17.00 (Astron) 2009-07-10.
    
    
    

    AUTHORS

           Rayan Zachariassen, University of Toronto, 1984
             ls-F and which builtins and numerous  bug  fixes,  modifications  and
             speedups
           Chris Kingsley, Caltech
             Fast storage allocator routines
           Chris Grevstad, TRW, 1987
             Incorporated 4.3BSD csh into tcsh
           Christos S. Zoulas, Cornell U. EE Dept., 1987-94
             Ports   to   HPUX,   SVR2  and  SVR3,  a  SysV  version  of  getwd.c,
             SHORT_STRINGS support and a new version of sh.glob.c
           James J Dempsey, BBN, and Paul Placeway, OSU, 1988
             A/UX port
           Daniel Long, NNSC, 1988
             wordchars
           Patrick Wolfe, Kuck and Associates, Inc., 1988
             vi mode cleanup
           David C Lawrence, Rensselaer Polytechnic Institute, 1989
             autolist and ambiguous completion listing
           Alec Wolman, DEC, 1989
             Newlines in the prompt
           Matt Landau, BBN, 1989
             ~/.tcshrc
           Ray Moody, Purdue Physics, 1989
             Magic space bar history expansion
           Mordechai ????, Intel, 1989
             printprompt() fixes and additions
           Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
             Automatic spelling correction and prompt3
           Per Hedeland, Ellemtel, Sweden, 1990-
             Various bugfixes, improvements and manual updates
           Hans J. Albertsson (Sun Sweden)
             ampm, settc and telltc
           Michael Bloom
             Interrupt handling fixes
           Michael Fine, Digital Equipment Corp
             Extended key support
           Eric Schnoebelen, Convex, 1990
             Convex support, lots of csh bug fixes, save and restore of  directory
             stack
           Ron Flax, Apple, 1990
             A/UX 2.0 (re)port
           Dan Oscarsson, LTH Sweden, 1990
             NLS support and simulated NLS support for non NLS sites, fixes
           Johan Widen, SICS Sweden, 1990
             shlvl, Mach support, correct-line, 8-bit printing
           Matt Day, Sanyo Icon, 1990
             POSIX termio support, SysV limit fixes
           Jaap Vermeulen, Sequent, 1990-91
             Vi mode fixes, expand-line, window change fixes, Symmetry port
           Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
             autolist  beeping  options, modified the history search to search for
             the whole string from the beginning of the line to the cursor.
             Coherent port
           Andy Phillips, Mullard Space Science Lab U.K., 1992
             VMS-POSIX port
           Beto Appleton, IBM Corp., 1992
             Walking  process  group fixes, csh bug fixes, POSIX file tests, POSIX
             SIGHUP
           Scott Bolte, Cray Computer Corp., 1992
             CSOS port
           Kaveh R. Ghazi, Rutgers University, 1992
             Tek, m88k, Titan and Masscomp ports and fixes.  Added  autoconf  sup-
             port.
           Mark Linderman, Cornell University, 1992
             OS/2 port
           Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992
             Linux port
           Tim P. Starrin, NASA Langley Research Center Operations, 1993
             Read-only variables
           Dave Schweisguth, Yale University, 1993-4
             New man page and tcsh.man2html
           Larry Schwimmer, Stanford University, 1993
             AFS and HESIOD patches
           Luke Mewburn, RMIT University, 1994-6
             Enhanced directory printing in prompt, added ellipsis and rprompt.
           Edward Hutchins, Silicon Graphics Inc., 1996
             Added implicit cd.
           Martin Kraemer, 1997
             Ported to Siemens Nixdorf EBCDIC machine
           Amol Deshpande, Microsoft, 1997
             Ported  to  WIN32  (Windows/95 and Windows/NT); wrote all the missing
             library and message catalog code to interface to Windows.
           Taga Nayuta, 1998
             Color ls additions.
    
    
    

    THANKS TO

           Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig,
           Diana  Smetters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all
           the other people at Ohio State for suggestions and encouragement
    
           All the people on the net, for putting up with, reporting bugs in,  and
           suggesting new additions to each and every version
    
           Richard M. Alderson III, for writing the 'T in tcsh' section
    
    
    

    Astron 6.17.00 10 July 2009 TCSH(1)

    
    
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