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    Command:

    fts_set

    
    
    
    

    SYNOPSIS

           #include <sys/types.h>
           #include <sys/stat.h>
           #include <fts.h>
    
           FTS *fts_open(char * const *path_argv, int options,
                         int (*compar)(const FTSENT **, const FTSENT **));
    
           FTSENT *fts_read(FTS *ftsp);
    
           FTSENT *fts_children(FTS *ftsp, int options);
    
           int fts_set(FTS *ftsp, FTSENT *f, int options);
    
           int fts_close(FTS *ftsp);
    
    
    

    DESCRIPTION

           The fts functions are provided for traversing file hierarchies.  A sim-
           ple  overview  is  that the fts_open() function returns a "handle" on a
           file hierarchy, which is then supplied to the other fts functions.  The
           function  fts_read() returns a pointer to a structure describing one of
           the files in the file hierarchy.  The function fts_children() returns a
           pointer  to a linked list of structures, each of which describes one of
           the files contained in a  directory  in  the  hierarchy.   In  general,
           directories  are visited two distinguishable times; in preorder (before
           any of their descendants are visited) and in postorder  (after  all  of
           their  descendants  have been visited).  Files are visited once.  It is
           possible to walk the hierarchy "logically"  (visiting  the  files  that
           symbolic  links  point  to)  or physically (visiting the symbolic links
           themselves), order the walk of the hierarchy or  prune  and/or  revisit
           portions of the hierarchy.
    
           Two structures are defined (and typedef'd) in the include file <fts.h>.
           The first is FTS, the structure  that  represents  the  file  hierarchy
           itself.   The second is FTSENT, the structure that represents a file in
           the file hierarchy.  Normally, an  FTSENT  structure  is  returned  for
           every  file  in  the  file  hierarchy.  In this manual page, "file" and
           "FTSENT structure" are generally interchangeable.  The FTSENT structure
           contains  at least the following fields, which are described in greater
           detail below:
    
               typedef struct _ftsent {
                   unsigned short fts_info;     /* flags for FTSENT structure */
                   char          *fts_accpath;  /* access path */
                   char          *fts_path;     /* root path */
                   short          fts_pathlen;  /* strlen(fts_path) */
                   char          *fts_name;     /* filename */
                   short          fts_namelen;  /* strlen(fts_name) */
                   short          fts_level;    /* depth (-1 to N) */
                   int            fts_errno;    /* file errno */
                   long           fts_number;   /* local numeric value */
    
                       FTS_D       A directory being visited in preorder.
    
                       FTS_DC      A directory that causes a cycle  in  the  tree.
                                   (The  fts_cycle  field  of the FTSENT structure
                                   will be filled in as well.)
    
                       FTS_DEFAULT Any FTSENT structure  that  represents  a  file
                                   type  not  explicitly  described  by one of the
                                   other fts_info values.
    
                       FTS_DNR     A directory which cannot be read.  This  is  an
                                   error  return,  and the fts_errno field will be
                                   set to indicate what caused the error.
    
                       FTS_DOT     A file named "."  or ".."  which was not speci-
                                   fied  as a filename to fts_open() (see FTS_SEE-
                                   DOT).
    
                       FTS_DP      A directory being visited  in  postorder.   The
                                   contents   of  the  FTSENT  structure  will  be
                                   unchanged from when it  was  returned  in  pre-
                                   order,  that is, with the fts_info field set to
                                   FTS_D.
    
                       FTS_ERR     This is an  error  return,  and  the  fts_errno
                                   field  will  be set to indicate what caused the
                                   error.
    
                       FTS_F       A regular file.
    
                       FTS_NS      A file for which  no  stat(2)  information  was
                                   available.  The contents of the fts_statp field
                                   are undefined.  This is an  error  return,  and
                                   the  fts_errno  field  will  be set to indicate
                                   what caused the error.
    
                       FTS_NSOK    A file for which  no  stat(2)  information  was
                                   requested.  The contents of the fts_statp field
                                   are undefined.
    
                       FTS_SL      A symbolic link.
    
                       FTS_SLNONE  A symbolic link with a nonexistent target.  The
                                   contents  of  the fts_statp field reference the
                                   file characteristic information  for  the  sym-
                                   bolic link itself.
    
           fts_accpath A path for accessing the file from the current directory.
    
           fts_path    The  path  for the file relative to the root of the traver-
                       sal.  This path contains the path specified  to  fts_open()
    
           fts_errno   Upon  return  of a FTSENT structure from the fts_children()
                       or fts_read() functions, with its  fts_info  field  set  to
                       FTS_DNR,  FTS_ERR  or  FTS_NS, the fts_errno field contains
                       the value of the external  variable  errno  specifying  the
                       cause  of  the  error.   Otherwise,  the  contents  of  the
                       fts_errno field are undefined.
    
           fts_number  This field is provided for the use of the application  pro-
                       gram  and is not modified by the fts functions.  It is ini-
                       tialized to 0.
    
           fts_pointer This field is provided for the use of the application  pro-
                       gram  and is not modified by the fts functions.  It is ini-
                       tialized to NULL.
    
           fts_parent  A pointer to the FTSENT structure referencing the  file  in
                       the  hierarchy immediately above the current file, that is,
                       the directory of which this file is  a  member.   A  parent
                       structure  for the initial entry point is provided as well,
                       however, only the  fts_level,  fts_number  and  fts_pointer
                       fields are guaranteed to be initialized.
    
           fts_link    Upon  return from the fts_children() function, the fts_link
                       field points to the next structure in  the  NULL-terminated
                       linked  list of directory members.  Otherwise, the contents
                       of the fts_link field are undefined.
    
           fts_cycle   If a  directory  causes  a  cycle  in  the  hierarchy  (see
                       FTS_DC), either because of a hard link between two directo-
                       ries, or a symbolic  link  pointing  to  a  directory,  the
                       fts_cycle  field  of the structure will point to the FTSENT
                       structure in the hierarchy that references the same file as
                       the  current  FTSENT structure.  Otherwise, the contents of
                       the fts_cycle field are undefined.
    
           fts_statp   A pointer to stat(2) information for the file.
    
           A single buffer is used for all of the paths of all of the files in the
           file  hierarchy.   Therefore,  the  fts_path and fts_accpath fields are
           guaranteed to be  null-terminated  only  for  the  file  most  recently
           returned  by  fts_read().   To  use these fields to reference any files
           represented by other FTSENT  structures  will  require  that  the  path
           buffer  be  modified  using  the  information  contained in that FTSENT
           structure's fts_pathlen field.  Any such modifications should be undone
           before  further  calls to fts_read() are attempted.  The fts_name field
           is always null-terminated.
    
       fts_open()
           The fts_open() function takes a pointer to an array of character point-
           ers  naming one or more paths which make up a logical file hierarchy to
           be traversed.  The array must be terminated by a null pointer.
    
                        tent  files.   Either  FTS_LOGICAL or FTS_PHYSICAL must be
                        provided to the fts_open() function.
    
           FTS_NOCHDIR  As a performance optimization, the  fts  functions  change
                        directories as they walk the file hierarchy.  This has the
                        side-effect that an application cannot rely  on  being  in
                        any   particular  directory  during  the  traversal.   The
                        FTS_NOCHDIR option turns off this  optimization,  and  the
                        fts functions will not change the current directory.  Note
                        that applications should not themselves change their  cur-
                        rent  directory and try to access files unless FTS_NOCHDIR
                        is specified and absolute pathnames were provided as argu-
                        ments to fts_open().
    
           FTS_NOSTAT   By  default,  returned  FTSENT  structures  reference file
                        characteristic information (the statp field) for each file
                        visited.   This  option relaxes that requirement as a per-
                        formance optimization, allowing the fts functions  to  set
                        the  fts_info  field to FTS_NSOK and leave the contents of
                        the statp field undefined.
    
           FTS_PHYSICAL This option causes  the  fts  routines  to  return  FTSENT
                        structures  for  symbolic  links themselves instead of the
                        target files they point to.  If this option is set, FTSENT
                        structures  for  all  symbolic  links in the hierarchy are
                        returned  to  the  application.   Either  FTS_LOGICAL   or
                        FTS_PHYSICAL  must be provided to the fts_open() function.
    
           FTS_SEEDOT   By default, unless they are specified as path arguments to
                        fts_open(),  any  files named "."  or ".."  encountered in
                        the file hierarchy are ignored.  This  option  causes  the
                        fts routines to return FTSENT structures for them.
    
           FTS_XDEV     This  option prevents fts from descending into directories
                        that have a different device number  than  the  file  from
                        which the descent began.
    
           The  argument  compar()  specifies a user-defined function which may be
           used to order the traversal of the hierarchy.  It takes two pointers to
           pointers to FTSENT structures as arguments and should return a negative
           value, zero, or a positive value to indicate if the file referenced  by
           its  first  argument  comes  before,  in  any order with respect to, or
           after, the file referenced by its second  argument.   The  fts_accpath,
           fts_path  and  fts_pathlen fields of the FTSENT structures may never be
           used in this comparison.  If the fts_info field is  set  to  FTS_NS  or
           FTS_NSOK, the fts_statp field may not either.  If the compar() argument
           is NULL, the directory traversal  order  is  in  the  order  listed  in
           path_argv  for the root paths, and in the order listed in the directory
           for everything else.
    
       fts_read()
           The fts_read() function  returns  a  pointer  to  an  FTSENT  structure
           The FTSENT structures returned by fts_read() may be overwritten after a
           call to fts_close() on the same file hierarchy stream, or, after a call
           to fts_read() on the same file hierarchy stream unless they represent a
           file of type directory, in which case  they  will  not  be  overwritten
           until  after  a  call to fts_read() after the FTSENT structure has been
           returned by the function fts_read() in postorder.
    
       fts_children()
           The fts_children() function returns a pointer to  an  FTSENT  structure
           describing  the  first  entry  in  a NULL-terminated linked list of the
           files in  the  directory  represented  by  the  FTSENT  structure  most
           recently  returned  by  fts_read().   The  list  is  linked through the
           fts_link field of the FTSENT structure, and is  ordered  by  the  user-
           specified  comparison  function,  if  any.  Repeated calls to fts_chil-
           dren() will re-create this linked list.
    
           As a special case, if fts_read() has not yet been called for a  hierar-
           chy,  fts_children()  will return a pointer to the files in the logical
           directory specified to fts_open(), that is, the arguments specified  to
           fts_open().   Otherwise, if the FTSENT structure most recently returned
           by fts_read() is not a directory being  visited  in  preorder,  or  the
           directory  does  not contain any files, fts_children() returns NULL and
           sets errno to zero.  If an error occurs,  fts_children()  returns  NULL
           and sets errno appropriately.
    
           The  FTSENT  structures  returned  by fts_children() may be overwritten
           after a call to fts_children(), fts_close() or fts_read() on  the  same
           file hierarchy stream.
    
           Option may be set to the following value:
    
           FTS_NAMEONLY Only  the  names of the files are needed.  The contents of
                        all the fields in the returned linked list  of  structures
                        are  undefined  with  the  exception  of  the fts_name and
                        fts_namelen fields.
    
       fts_set()
           The function fts_set() allows the user application to determine further
           processing  for  the file f of the stream ftsp.  The fts_set() function
           returns 0 on success, and -1 if an error occurs.  Option must be set to
           one of the following values:
    
           FTS_AGAIN    Revisit  the  file;  any  file type may be revisited.  The
                        next call to fts_read() will return the  referenced  file.
                        The  fts_stat and fts_info fields of the structure will be
                        reinitialized at that time, but no other fields will  have
                        been changed.  This option is meaningful only for the most
                        recently returned file from fts_read().  Normal use is for
                        postorder  directory visits, where it causes the directory
                        to be revisited (in both preorder and postorder)  as  well
                        as all of its descendants.
    
                        If  the  target  of  the link is a directory, the preorder
                        return, followed by the return of all of its  descendants,
                        followed by a postorder return, is done.
    
           FTS_SKIP     No  descendants of this file are visited.  The file may be
                        one of those most recently returned  by  either  fts_chil-
                        dren() or fts_read().
    
       fts_close()
           The  fts_close()  function  closes  a  file  hierarchy  stream ftsp and
           restores the current directory to the directory from  which  fts_open()
           was  called  to  open ftsp.  The fts_close() function returns 0 on suc-
           cess, and -1 if an error occurs.
    
    
    

    ERRORS

           The function fts_open() may fail and set errno for any  of  the  errors
           specified for open(2) and malloc(3).
    
           The  function  fts_close() may fail and set errno for any of the errors
           specified for chdir(2) and close(2).
    
           The functions fts_read() and fts_children() may fail and set errno  for
           any  of the errors specified for chdir(2), malloc(3), opendir(3), read-
           dir(3) and stat(2).
    
           In addition, fts_children(), fts_open() and fts_set() may fail and  set
           errno as follows:
    
           EINVAL The options were invalid.
    
    
    

    VERSIONS

           These functions are available in Linux since glibc2.
    
    
    

    CONFORMING TO

           4.4BSD.
    
    
    

    BUGS

           All  of the APIs described in this man page are not safe when compiling
           a program using the LFS APIs (e.g., when  compiling  with  -D_FILE_OFF-
           SET_BITS=64).
    
    
    

    SEE ALSO

           find(1), chdir(2), stat(2), ftw(3), qsort(3)
    
    
    

    Linux 2014-03-18 FTS(3)

    
    
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