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    Command:

    sudo

    
         sudo -v [-AknS] [-g group name | #gid] [-p prompt] [-u user name | #uid]
         sudo -l[l] [-AknS] [-g group name | #gid] [-p prompt] [-U user name]
              [-u user name | #uid] [command]
         sudo [-AbEHnPS] [-C fd] [-g group name | #gid] [-p prompt] [-r role]
              [-t type] [-u user name | #uid] [VAR=value] -i | -s [command]
         sudoedit [-AnS] [-C fd] [-g group name | #gid] [-p prompt]
              [-u user name | #uid] file ...
    
    
    

    DESCRIPTION

         sudo allows a permitted user to execute a command as the superuser or
         another user, as specified by the security policy.
    
         sudo supports a plugin architecture for security policies and input/out-
         put logging.  Third parties can develop and distribute their own policy
         and I/O logging plugins to work seamlessly with the sudo front end.  The
         default security policy is sudoers, which is configured via the file
         /etc/sudoers, or via LDAP.  See the PLUGINS section for more information.
    
         The security policy determines what privileges, if any, a user has to run
         sudo.  The policy may require that users authenticate themselves with a
         password or another authentication mechanism.  If authentication is
         required, sudo will exit if the user's password is not entered within a
         configurable time limit.  This limit is policy-specific; the default
         password prompt timeout for the sudoers security policy is 5 minutes.
    
         Security policies may support credential caching to allow the user to run
         sudo again for a period of time without requiring authentication.  The
         sudoers policy caches credentials for 5 minutes, unless overridden in
         sudoers(5).  By running sudo with the -v option, a user can update the
         cached credentials without running a command.
    
         When invoked as sudoedit, the -e option (described below), is implied.
    
         Security policies may log successful and failed attempts to use sudo.  If
         an I/O plugin is configured, the running command's input and output may
         be logged as well.
    
         The options are as follows:
    
         -A          Normally, if sudo requires a password, it will read it from
                     the user's terminal.  If the -A (askpass) option is speci-
                     fied, a (possibly graphical) helper program is executed to
                     read the user's password and output the password to the stan-
                     dard output.  If the SUDO_ASKPASS environment variable is
                     set, it specifies the path to the helper program.  Otherwise,
                     if /etc/sudo.conf contains a line specifying the askpass pro-
                     gram, that value will be used.  For example:
    
                         # Path to askpass helper program
                         Path askpass /usr/X11R6/bin/ssh-askpass
    
                     If no askpass program is available, sudo will exit with an
                     sudoers policy only permits use of the -C option when the
                     administrator has enabled the closefrom_override option.
    
         -E          The -E (preserve environment) option indicates to the secu-
                     rity policy that the user wishes to preserve their existing
                     environment variables.  The security policy may return an
                     error if the -E option is specified and the user does not
                     have permission to preserve the environment.
    
         -e          The -e (edit) option indicates that, instead of running a
                     command, the user wishes to edit one or more files.  In lieu
                     of a command, the string "sudoedit" is used when consulting
                     the security policy.  If the user is authorized by the pol-
                     icy, the following steps are taken:
    
                     1.   Temporary copies are made of the files to be edited with
                          the owner set to the invoking user.
    
                     2.   The editor specified by the policy is run to edit the
                          temporary files.  The sudoers policy uses the
                          SUDO_EDITOR, VISUAL and EDITOR environment variables (in
                          that order).  If none of SUDO_EDITOR, VISUAL or EDITOR
                          are set, the first program listed in the editor
                          sudoers(5) option is used.
    
                     3.   If they have been modified, the temporary files are
                          copied back to their original location and the temporary
                          versions are removed.
    
                     If the specified file does not exist, it will be created.
                     Note that unlike most commands run by sudo, the editor is run
                     with the invoking user's environment unmodified.  If, for
                     some reason, sudo is unable to update a file with its edited
                     version, the user will receive a warning and the edited copy
                     will remain in a temporary file.
    
         -g group    Normally, sudo runs a command with the primary group set to
                     the one specified by the password database for the user the
                     command is being run as (by default, root).  The -g (group)
                     option causes sudo to run the command with the primary group
                     set to group instead.  To specify a gid instead of a group
                     name, use #gid.  When running commands as a gid, many shells
                     require that the '#' be escaped with a backslash ('\').  If
                     no -u option is specified, the command will be run as the
                     invoking user (not root).  In either case, the primary group
                     will be set to group.
    
         -H          The -H (HOME) option requests that the security policy set
                     the HOME environment variable to the home directory of the
                     target user (root by default) as specified by the password
                     database.  Depending on the policy, this may be the default
                     behavior.
                     set of variables, similar to what is present when a user logs
                     in.  The Command Environment section in the sudoers(5) manual
                     documents how the -i option affects the environment in which
                     a command is run when the sudoers policy is in use.
    
         -K          The -K (sure kill) option is like -k except that it removes
                     the user's cached credentials entirely and may not be used in
                     conjunction with a command or other option.  This option does
                     not require a password.  Not all security policies support
                     credential caching.
    
         -k [command]
                     When used alone, the -k (kill) option to sudo invalidates the
                     user's cached credentials.  The next time sudo is run a pass-
                     word will be required.  This option does not require a pass-
                     word and was added to allow a user to revoke sudo permissions
                     from a .logout file.  Not all security policies support cre-
                     dential caching.
    
                     When used in conjunction with a command or an option that may
                     require a password, the -k option will cause sudo to ignore
                     the user's cached credentials.  As a result, sudo will prompt
                     for a password (if one is required by the security policy)
                     and will not update the user's cached credentials.
    
         -l[l] [command]
                     If no command is specified, the -l (list) option will list
                     the allowed (and forbidden) commands for the invoking user
                     (or the user specified by the -U option) on the current host.
                     If a command is specified and is permitted by the security
                     policy, the fully-qualified path to the command is displayed
                     along with any command line arguments.  If command is speci-
                     fied but not allowed, sudo will exit with a status value of
                     1.  If the -l option is specified with an l argument (i.e.
                     -ll), or if -l is specified multiple times, a longer list
                     format is used.
    
         -n          The -n (non-interactive) option prevents sudo from prompting
                     the user for a password.  If a password is required for the
                     command to run, sudo will display an error message and exit.
    
         -P          The -P (preserve group vector) option causes sudo to preserve
                     the invoking user's group vector unaltered.  By default, the
                     sudoers policy will initialize the group vector to the list
                     of groups the target user is in.  The real and effective
                     group IDs, however, are still set to match the target user.
    
         -p prompt   The -p (prompt) option allows you to override the default
                     password prompt and use a custom one.  The following percent
                     ('%') escapes are supported by the sudoers policy:
    
                     %H  expanded to the host name including the domain name (on
    
                     %%  two consecutive '%' characters are collapsed into a sin-
                         gle '%' character
    
                     The prompt specified by the -p option will override the sys-
                     tem password prompt on systems that support PAM unless the
                     passprompt_override flag is disabled in sudoers.
    
         -r role     The -r (role) option causes the new (SELinux) security con-
                     text to have the role specified by role.
    
         -S          The -S (stdin) option causes sudo to read the password from
                     the standard input instead of the terminal device.  The pass-
                     word must be followed by a newline character.
    
         -s [command]
                     The -s (shell) option runs the shell specified by the SHELL
                     environment variable if it is set or the shell as specified
                     in the password database.  If a command is specified, it is
                     passed to the shell for execution via the shell's -c option.
                     If no command is specified, an interactive shell is executed.
    
         -t type     The -t (type) option causes the new (SELinux) security con-
                     text to have the type specified by type.  If no type is spec-
                     ified, the default type is derived from the specified role.
    
         -U user     The -U (other user) option is used in conjunction with the -l
                     option to specify the user whose privileges should be listed.
                     The security policy may restrict listing other users' privi-
                     leges.  The sudoers policy only allows root or a user with
                     the ALL privilege on the current host to use this option.
    
         -u user     The -u (user) option causes sudo to run the specified command
                     as a user other than root.  To specify a uid instead of a
                     user name, #uid.  When running commands as a uid, many shells
                     require that the '#' be escaped with a backslash ('\').
                     Security policies may restrict uids to those listed in the
                     password database.  The sudoers policy allows uids that are
                     not in the password database as long as the targetpw option
                     is not set.  Other security policies may not support this.
    
         -V          The -V (version) option causes sudo to print its version
                     string and the version string of the security policy plugin
                     and any I/O plugins.  If the invoking user is already root
                     the -V option will display the arguments passed to configure
                     when sudo was built and plugins may display more verbose
                     information such as default options.
    
         -v          When given the -v (validate) option, sudo will update the
                     user's cached credentials, authenticating the user's password
                     if necessary.  For the sudoers plugin, this extends the sudo
                     timeout for another 5 minutes (or whatever the timeout is set
    
    
    

    COMMAND EXECUTION

         When sudo executes a command, the security policy specifies the execution
         envionment for the command.  Typically, the real and effective uid and
         gid are set to match those of the target user, as specified in the pass-
         word database, and the group vector is initialized based on the group
         database (unless the -P option was specified).
    
         The following parameters may be specified by security policy:
    
         ?   real and effective user ID
    
         ?   real and effective group ID
    
         ?   supplementary group IDs
    
         ?   the environment list
    
         ?   current working directory
    
         ?   file creation mode mask (umask)
    
         ?   SELinux role and type
    
         ?   scheduling priority (aka nice value)
    
       Process model
         When sudo runs a command, it calls fork(2), sets up the execution envi-
         ronment as described above, and calls the execve system call in the child
         process.  The main sudo process waits until the command has completed,
         then passes the command's exit status to the security policy's close
         method and exits.  If an I/O logging plugin is configured, a new  pseudo-
         terminal ("pty") is created and a second sudo process is used to relay
         job control signals between the user's existing pty and the new pty the
         command is being run in.  This extra process makes it possible to, for
         example, suspend and resume the command.  Without it, the command would
         be in what POSIX terms an "orphaned process group" and it would not
         receive any job control signals.
    
       Signal handling
         Because the command is run as a child of the sudo process, sudo will
         relay signals it receives to the command.  Unless the command is being
         run in a new pty, the SIGHUP, SIGINT and SIGQUIT signals are not relayed
         unless they are sent by a user process, not the kernel.  Otherwise, the
         command would receive SIGINT twice every time the user entered control-C.
         Some signals, such as SIGSTOP and SIGKILL, cannot be caught and thus will
         not be relayed to the command.  As a general rule, SIGTSTP should be used
         instead of SIGSTOP when you wish to suspend a command being run by sudo.
    
         As a special case, sudo will not relay signals that were sent by the com-
         mand it is running.  This prevents the command from accidentally killing
         itself.  On some systems, the reboot(8) command sends SIGTERM to all non-
         tains no Plugin lines, sudo will use the traditional sudoers security
         policy and I/O logging, which corresponds to the following /etc/sudo.conf
         file.
    
         #
         # Default /etc/sudo.conf file
         #
         # Format:
         #   Plugin plugin_name plugin_path plugin_options ...
         #   Path askpass /path/to/askpass
         #   Path noexec /path/to/sudo_noexec.so
         #   Debug sudo /var/log/sudo_debug all@warn
         #   Set disable_coredump true
         #
         # The plugin_path is relative to /usr/libexec unless
         #   fully qualified.
         # The plugin_name corresponds to a global symbol in the plugin
         #   that contains the plugin interface structure.
         # The plugin_options are optional.
         #
         Plugin policy_plugin sudoers.so
         Plugin io_plugin sudoers.so
    
         A Plugin line consists of the Plugin keyword, followed by the symbol_name
         and the path to the shared object containing the plugin.  The symbol_name
         is the name of the struct policy_plugin or struct io_plugin in the plugin
         shared object.  The path may be fully qualified or relative.  If not
         fully qualified it is relative to the /usr/libexec directory.  Any addi-
         tional parameters after the path are passed as arguments to the plugin's
         open function.  Lines that don't begin with Plugin, Path, Debug, or Set
         are silently ignored.
    
         For more information, see the sudo_plugin(8) manual.
    
    
    

    PATHS

         A Path line consists of the Path keyword, followed by the name of the
         path to set and its value.  E.g.
    
               Path noexec /usr/libexec/sudo_noexec.so
               Path askpass /usr/X11R6/bin/ssh-askpass
    
         The following plugin-agnostic paths may be set in the /etc/sudo.conf
         file:
    
         askpass   The fully qualified path to a helper program used to read the
                   user's password when no terminal is available.  This may be the
                   case when sudo is executed from a graphical (as opposed to
                   text-based) application.  The program specified by askpass
                   should display the argument passed to it as the prompt and
                   write the user's password to the standard output.  The value of
                   askpass may be overridden by the SUDO_ASKPASS environment vari-
                   able.
    
         comma-separated list of debug flags.  The debug flag syntax used by sudo
         and the sudoers plugin is subsystem@priority but the plugin is free to
         use a different format so long as it does not include a comma (',').
    
         For instance:
    
               Debug sudo /var/log/sudo_debug all@warn,plugin@info
    
         would log all debugging statements at the warn level and higher in addi-
         tion to those at the info level for the plugin subsystem.
    
         Currently, only one Debug entry per program is supported.  The sudo Debug
         entry is shared by the sudo front end, sudoedit and the plugins.  A
         future release may add support for per-plugin Debug lines and/or support
         for multiple debugging files for a single program.
    
         The priorities used by the sudo front end, in order of decreasing sever-
         ity, are: crit, err, warn, notice, diag, info, trace and debug.  Each
         priority, when specified, also includes all priorities higher than it.
         For example, a priority of notice would include debug messages logged at
         notice and higher.
    
         The following subsystems are used by the sudo front-end:
    
         all         matches every subsystem
    
         args        command line argument processing
    
         conv        user conversation
    
         edit        sudoedit
    
         exec        command execution
    
         main        sudo main function
    
         netif       network interface handling
    
         pcomm       communication with the plugin
    
         plugin      plugin configuration
    
         pty         pseudo-tty related code
    
         selinux     SELinux-specific handling
    
         util        utility functions
    
         utmp        utmp handling
    
    
    

    EXIT VALUE

         Upon successful execution of a program, the exit status from sudo will
         sudo tries to be safe when executing external commands.
    
         To prevent command spoofing, sudo checks "." and "" (both denoting cur-
         rent directory) last when searching for a command in the user's PATH (if
         one or both are in the PATH).  Note, however, that the actual PATH envi-
         ronment variable is not modified and is passed unchanged to the program
         that sudo executes.
    
         Please note that sudo will normally only log the command it explicitly
         runs.  If a user runs a command such as sudo su or sudo sh, subsequent
         commands run from that shell are not subject to sudo's security policy.
         The same is true for commands that offer shell escapes (including most
         editors).  If I/O logging is enabled, subsequent commands will have their
         input and/or output logged, but there will not be traditional logs for
         those commands.  Because of this, care must be taken when giving users
         access to commands via sudo to verify that the command does not inadver-
         tently give the user an effective root shell.  For more information,
         please see the PREVENTING SHELL ESCAPES section in sudoers(5).
    
         To prevent the disclosure of potentially sensitive information, sudo dis-
         ables core dumps by default while it is executing (they are re-enabled
         for the command that is run).  To aid in debugging sudo crashes, you may
         wish to re-enable core dumps by setting "disable_coredump" to false in
         the /etc/sudo.conf file as follows:
    
               Set disable_coredump false
    
         Note that by default, most operating systems disable core dumps from
         setuid programs, which includes sudo.  To actually get a sudo core file
         you may need to enable core dumps for setuid processes.  On BSD and Linux
         systems this is accomplished via the sysctl command, on Solaris the core-
         adm command can be used.
    
    
    

    ENVIRONMENT

         sudo utilizes the following environment variables.  The security policy
         has control over the actual content of the command's environment.
    
         EDITOR           Default editor to use in -e (sudoedit) mode if neither
                          SUDO_EDITOR nor VISUAL is set.
    
         MAIL             In -i mode or when env_reset is enabled in sudoers, set
                          to the mail spool of the target user.
    
         HOME             Set to the home directory of the target user if -i or -H
                          are specified, env_reset or always_set_home are set in
                          sudoers, or when the -s option is specified and set_home
                          is set in sudoers.
    
         PATH             May be overridden by the security policy.
    
         SHELL            Used to determine shell to run with -s option.
    
    
         SUDO_UID         Set to the user ID of the user who invoked sudo.
    
         SUDO_USER        Set to the login name of the user who invoked sudo.
    
         USER             Set to the target user (root unless the -u option is
                          specified).
    
         VISUAL           Default editor to use in -e (sudoedit) mode if
                          SUDO_EDITOR is not set.
    
    
    

    FILES

         /etc/sudo.conf            sudo front end configuration
    
    
    

    EXAMPLES

         Note: the following examples assume a properly configured security pol-
         icy.
    
         To get a file listing of an unreadable directory:
    
               $ sudo ls /usr/local/protected
    
         To list the home directory of user yaz on a machine where the file system
         holding ~yaz is not exported as root:
    
               $ sudo -u yaz ls ~yaz
    
         To edit the index.html file as user www:
    
               $ sudo -u www vi ~www/htdocs/index.html
    
         To view system logs only accessible to root and users in the adm group:
    
               $ sudo -g adm view /var/log/syslog
    
         To run an editor as jim with a different primary group:
    
               $ sudo -u jim -g audio vi ~jim/sound.txt
    
         To shut down a machine:
    
               $ sudo shutdown -r +15 "quick reboot"
    
         To make a usage listing of the directories in the /home partition.  Note
         that this runs the commands in a sub-shell to make the cd and file redi-
         rection work.
    
               $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE"
    
    
    

    SEE ALSO

         grep(1), su(1), stat(2), passwd(5), sudoers(5), sudo_plugin(8),
         sudoreplay(8), visudo(8)
    
    
    

    CAVEATS

         There is no easy way to prevent a user from gaining a root shell if that
         user is allowed to run arbitrary commands via sudo.  Also, many programs
         (such as editors) allow the user to run commands via shell escapes, thus
         avoiding sudo's checks.  However, on most systems it is possible to pre-
         vent shell escapes with the sudoers(5) plugin's noexec functionality.
    
         It is not meaningful to run the cd command directly via sudo, e.g.,
    
               $ sudo cd /usr/local/protected
    
         since when the command exits the parent process (your shell) will still
         be the same.  Please see the EXAMPLES section for more information.
    
         Running shell scripts via sudo can expose the same kernel bugs that make
         setuid shell scripts unsafe on some operating systems (if your OS has a
         /dev/fd/ directory, setuid shell scripts are generally safe).
    
    
    

    BUGS

         If you feel you have found a bug in sudo, please submit a bug report at
         http://www.sudo.ws/sudo/bugs/
    
    
    

    SUPPORT

         Limited free support is available via the sudo-users mailing list, see
         http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the
         archives.
    
    
    

    DISCLAIMER

         sudo is provided "AS IS" and any express or implied warranties, includ-
         ing, but not limited to, the implied warranties of merchantability and
         fitness for a particular purpose are disclaimed.  See the LICENSE file
         distributed with sudo or http://www.sudo.ws/sudo/license.html for com-
         plete details.
    
    
    

    Sudo 1.8.6p3 July 10, 2012 Sudo 1.8.6p3

    
    
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