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SUDO(8)			     MAINTENANCE COMMANDS		       SUDO(8)



NAME
       sudo, sudoedit - execute a command as another user

SYNOPSIS
       sudo -h | -K | -k | -L | -V

       sudo -v [-AknS] [-p prompt]

       sudo -l[l] [-AknS] [-g groupname|#gid] [-p prompt] [-U username]
       [-u username|#uid] [command]

       sudo [-AbEHnPS] [-C fd] [-g groupname|#gid] [-p prompt] [-r role]
       [-t type] [-u username|#uid] [VAR=value] [-i | -s] [command]

       sudoedit [-AnS] [-C fd] [-g groupname|#gid] [-p prompt]
       [-u username|#uid] file ...

DESCRIPTION
       sudo allows a permitted user to execute a command as the superuser or
       another user, as specified in the sudoers file.	The real and effective
       uid and gid are set to match those of the target user as specified in
       the passwd file and the group vector is initialized based on the group
       file (unless the -P option was specified).  If the invoking user is
       root or if the target user is the same as the invoking user, no
       password is required.  Otherwise, sudo requires that users authenticate
       themselves with a password by default (NOTE: in the default
       configuration this is the user's password, not the root password).
       Once a user has been authenticated, a timestamp is updated and the user
       may then use sudo without a password for a short period of time (5
       minutes unless overridden in sudoers).

       When invoked as sudoedit, the -e option (described below), is implied.

       sudo determines who is an authorized user by consulting the file
       /etc/sudoers.  By running sudo with the -v option, a user can update
       the time stamp without running a command. The password prompt itself
       will also time out if the user's password is not entered within 5
       minutes (unless overridden via sudoers).

       If a user who is not listed in the sudoers file tries to run a command
       via sudo, mail is sent to the proper authorities, as defined at
       configure time or in the sudoers file (defaults to root).  Note that
       the mail will not be sent if an unauthorized user tries to run sudo
       with the -l or -v option.  This allows users to determine for
       themselves whether or not they are allowed to use sudo.

       If sudo is run by root and the SUDO_USER environment variable is set,
       sudo will use this value to determine who the actual user is.  This can
       be used by a user to log commands through sudo even when a root shell
       has been invoked.  It also allows the -e option to remain useful even
       when being run via a sudo-run script or program.	 Note however, that
       the sudoers lookup is still done for root, not the user specified by
       SUDO_USER.

       sudo can log both successful and unsuccessful attempts (as well as
       errors) to syslog(3), a log file, or both.  By default sudo will log
       via syslog(3) but this is changeable at configure time or via the
       sudoers file.

OPTIONS
       sudo accepts the following command line options:

       -A	   Normally, if sudo requires a password, it will read it from
		   the current terminal.  If the -A (askpass) option is
		   specified, a (possibly graphical) helper program is
		   executed to read the user's password and output the
		   password to the standard output.  If the SUDO_ASKPASS
		   environment variable is set, it specifies the path to the
		   helper program.  Otherwise, the value specified by the
		   askpass option in sudoers(5) is used.

       -b	   The -b (background) option tells sudo to run the given
		   command in the background.  Note that if you use the -b
		   option you cannot use shell job control to manipulate the
		   process.

       -C fd	   Normally, sudo will close all open file descriptors other
		   than standard input, standard output and standard error.
		   The -C (close from) option allows the user to specify a
		   starting point above the standard error (file descriptor
		   three).  Values less than three are not permitted.  This
		   option is only available if the administrator has enabled
		   the closefrom_override option in sudoers(5).

       -E	   The -E (preserve environment) option will override the
		   env_reset option in sudoers(5)).  It is only available when
		   either the matching command has the SETENV tag or the
		   setenv option is set in sudoers(5).

       -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 sudoers file.	 If the user is authorized by
		   sudoers 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 SUDO_EDITOR, VISUAL or
		       EDITOR environment variables is run to edit the
		       temporary files.	 If none of SUDO_EDITOR, VISUAL or
		       EDITOR are set, the first program listed in the editor
		       sudoers variable 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 sets the primary group to the one specified
		   by the passwd database for the user the command is being
		   run as (by default, root).  The -g (group) option causes
		   sudo to run the specified command with the primary group
		   set to group.  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 sets the HOME environment variable to
		   the homedir of the target user (root by default) as
		   specified in passwd(5).  By default, sudo does not modify
		   HOME (see set_home and always_set_home in sudoers(5)).

       -h	   The -h (help) option causes sudo to print a usage message
		   and exit.

       -i [command]
		   The -i (simulate initial login) option runs the shell
		   specified in the passwd(5) entry of the target user as a
		   login shell.	 This means that login-specific resource files
		   such as .profile or .login will be read by the shell.  If a
		   command is specified, it is passed to the shell for
		   execution.  Otherwise, an interactive shell is executed.
		   sudo attempts to change to that user's home directory
		   before running the shell.  It also initializes the
		   environment, leaving DISPLAY and TERM unchanged, setting
		   HOME, SHELL, USER, LOGNAME, and PATH, as well as the
		   contents of /etc/environment on Linux and AIX systems.  All
		   other environment variables are removed.

       -K	   The -K (sure kill) option is like -k except that it removes
		   the user's timestamp entirely and may not be used in
		   conjunction with a command or other option.	This option
		   does not require a password.

       -k	   When used by itself, the -k (kill) option to sudo
		   invalidates the user's timestamp by setting the time on it
		   to the Epoch.  The next time sudo is run a password will be
		   required.  This option does not require a password and was
		   added to allow a user to revoke sudo permissions from a
		   .logout file.

		   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 timestamp file.  As a result, sudo will
		   prompt for a password (if one is required by sudoers) and
		   will not update the user's timestamp file.

       -L	   The -L (list defaults) option will list out the parameters
		   that may be set in a Defaults line along with a short
		   description for each.  This option is useful in conjunction
		   with grep(1).

       -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
		   sudoers, the fully-qualified path to the command is
		   displayed along with any command line arguments.  If
		   command is specified 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
		   messages and exit.

       -P	   The -P (preserve group vector) option causes sudo to
		   preserve the invoking user's group vector unaltered.	 By
		   default, sudo 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:

		   %H  expanded to the local hostname including the domain
		       name (on if the machine's hostname is fully qualified
		       or the fqdn sudoers option is set)

		   %h  expanded to the local hostname without the domain name

		   %p  expanded to the user whose password is being asked for
		       (respects the rootpw, targetpw and runaspw flags in
		       sudoers)

		   %U  expanded to the login name of the user the command will
		       be run as (defaults to root)

		   %u  expanded to the invoking user's login name

		   %%  two consecutive % characters are collapsed into a
		       single % character

		   The prompt specified by the -p option will override the
		   system 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
		   context 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.

       -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 passwd(5).  If a command is specified, it is passed to
		   the shell for execution.  Otherwise, an interactive shell
		   is executed.

       -t type	   The -t (type) option causes the new (SELinux) security
		   context to have the type specified by type.	If no type is
		   specified, 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.  Only root or a user with sudo ALL on the current
		   host may 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, use #uid.  When running commands as
		   a uid, many shells require that the '#' be escaped with a
		   backslash ('\').  Note that if the targetpw Defaults option
		   is set (see sudoers(5)) it is not possible to run commands
		   with a uid not listed in the password database.

       -V	   The -V (version) option causes sudo to print the version
		   number and exit.  If the invoking user is already root the
		   -V option will print out a list of the defaults sudo was
		   compiled with as well as the machine's local network
		   addresses.

       -v	   If given the -v (validate) option, sudo will update the
		   user's timestamp, prompting for the user's password if
		   necessary.  This extends the sudo timeout for another 5
		   minutes (or whatever the timeout is set to in sudoers) but
		   does not run a command.

       --	   The -- option indicates that sudo should stop processing
		   command line arguments.  It is most useful in conjunction
		   with the -s option.

       Environment variables to be set for the command may also be passed on
       the command line in the form of VAR=value, e.g.
       LD_LIBRARY_PATH=/usr/local/pkg/lib.  Variables passed on the command
       line are subject to the same restrictions as normal environment
       variables with one important exception.	If the setenv option is set in
       sudoers, the command to be run has the SETENV tag set or the command
       matched is ALL, the user may set variables that would overwise be
       forbidden.  See sudoers(5) for more information.

RETURN VALUES
       Upon successful execution of a program, the exit status from sudo will
       simply be the exit status of the program that was executed.

       Otherwise, sudo quits with an exit value of 1 if there is a
       configuration/permission problem or if sudo cannot execute the given
       command.	 In the latter case the error string is printed to stderr.  If
       sudo cannot stat(2) one or more entries in the user's PATH an error is
       printed on stderr.  (If the directory does not exist or if it is not
       really a directory, the entry is ignored and no error is printed.)
       This should not happen under normal circumstances.  The most common
       reason for stat(2) to return "permission denied" is if you are running
       an automounter and one of the directories in your PATH is on a machine
       that is currently unreachable.

SECURITY NOTES
       sudo tries to be safe when executing external commands.

       There are two distinct ways to deal with environment variables.	By
       default, the env_reset sudoers option is enabled.  This causes commands
       to be executed with a minimal environment containing TERM, PATH, HOME,
       SHELL, LOGNAME, USER and USERNAME in addition to variables from the
       invoking process permitted by the env_check and env_keep sudoers
       options.	 There is effectively a whitelist for environment variables.

       If, however, the env_reset option is disabled in sudoers, any variables
       not explicitly denied by the env_check and env_delete options are
       inherited from the invoking process.  In this case, env_check and
       env_delete behave like a blacklist.  Since it is not possible to
       blacklist all potentially dangerous environment variables, use of the
       default env_reset behavior is encouraged.

       In all cases, environment variables with a value beginning with () are
       removed as they could be interpreted as bash functions.	The list of
       environment variables that sudo allows or denies is contained in the
       output of sudo -V when run as root.

       Note that the dynamic linker on most operating systems will remove
       variables that can control dynamic linking from the environment of
       setuid executables, including sudo.  Depending on the operating system
       this may include _RLD*, DYLD_*, LD_*, LDR_*, LIBPATH, SHLIB_PATH, and
       others.	These type of variables are removed from the environment
       before sudo even begins execution and, as such, it is not possible for
       sudo to preserve them.

       To prevent command spoofing, sudo checks "." and "" (both denoting
       current 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
       environment variable is not modified and is passed unchanged to the
       program that sudo executes.

       sudo will check the ownership of its timestamp directory (/var/run/sudo
       by default) and ignore the directory's contents if it is not owned by
       root or if it is writable by a user other than root.  On systems that
       allow non-root users to give away files via chown(2), if the timestamp
       directory is located in a directory writable by anyone (e.g., /tmp), it
       is possible for a user to create the timestamp directory before sudo is
       run.  However, because sudo checks the ownership and mode of the
       directory and its contents, the only damage that can be done is to
       "hide" files by putting them in the timestamp dir.  This is unlikely to
       happen since once the timestamp dir is owned by root and inaccessible
       by any other user, the user placing files there would be unable to get
       them back out.  To get around this issue you can use a directory that
       is not world-writable for the timestamps (/var/adm/sudo for instance)
       or create /var/run/sudo with the appropriate owner (root) and
       permissions (0700) in the system startup files.

       sudo will not honor timestamps set far in the future.  Timestamps with
       a date greater than current_time + 2 * TIMEOUT will be ignored and sudo
       will log and complain.  This is done to keep a user from creating
       his/her own timestamp with a bogus date on systems that allow users to
       give away files.

       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 will not be logged, nor will sudo's access
       control affect them.  The same is true for commands that offer shell
       escapes (including most editors).  Because of this, care must be taken
       when giving users access to commands via sudo to verify that the
       command does not inadvertently give the user an effective root shell.
       For more information, please see the PREVENTING SHELL ESCAPES section
       in sudoers(5).

ENVIRONMENT
       sudo utilizes the following environment variables:

       EDITOR	       Default editor to use in -e (sudoedit) mode if neither
		       SUDO_EDITOR nor VISUAL is set

       HOME	       In -s or -H mode (or if sudo was configured with the
		       --enable-shell-sets-home option), set to homedir of the
		       target user

       PATH	       Set to a sane value if the secure_path sudoers option
		       is set.

       SHELL	       Used to determine shell to run with -s option

       SUDO_ASKPASS    Specifies the path to a helper program used to read the
		       password if no terminal is available or if the -A
		       option is specified.

       SUDO_COMMAND    Set to the command run by sudo

       SUDO_EDITOR     Default editor to use in -e (sudoedit) mode

       SUDO_GID	       Set to the group ID of the user who invoked sudo

       SUDO_PROMPT     Used as the default password prompt

       SUDO_PS1	       If set, PS1 will be set to its value for the program
		       being run

       SUDO_UID	       Set to the user ID of the user who invoked sudo

       SUDO_USER       Set to the login 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/sudoers	       List of who can run what

       /var/run/sudo	       Directory containing timestamps

       /etc/environment	       Initial environment for -i mode on Linux and
			       AIX

EXAMPLES
       Note: the following examples assume suitable sudoers(5) entries.

       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 shutdown 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
       redirection work.

	$ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE"

SEE ALSO
       grep(1), su(1), stat(2), passwd(5), sudoers(5), visudo(8)

AUTHORS
       Many people have worked on sudo over the years; this version consists
       of code written primarily by:

	       Todd C. Miller

       See the HISTORY file in the sudo distribution or visit
       http://www.sudo.ws/sudo/history.html for a short history of sudo.

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 prevent shell escapes with sudo's noexec functionality.
       See the sudoers(5) manual for details.

       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.

       If users have sudo ALL there is nothing to prevent them from creating
       their own program that gives them a root shell regardless of any '!'
       elements in the user specification.

       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,
       including, 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 complete details.



1.7.2p1				 June 15, 2009			       SUDO(8)
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