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SUDO(8)			  BSD System Manager's Manual		       SUDO(8)

     sudo, sudoedit -- execute a command as another user

     sudo -h | -K | -k | -V
     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 ...

     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

     -b		 The -b (background) option tells sudo to run the given com-
		 mand in the background.  Note that if you use the -b option
		 you cannot use shell job control to manipulate the process.
		 Most interactive commands will fail to work properly in back-
		 ground mode.

     -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).  Val-
		 ues less than three are not permitted.	 The security policy
		 may restrict the user's ability to use the -C option.	The
		 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

     -h		 The -h (help) option causes sudo to print a short help mes-
		 sage to the standard output and exit.

     -i [command]
		 The -i (simulate initial login) option runs the shell speci-
		 fied by the password database 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
		 via the shell's -c option.  If no command is specified, an
		 interactive shell is executed.	 sudo attempts to change to
		 that user's home directory before running the shell.  The
		 security policy shall initialize the environment to a minimal
		 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
		     if the machine's host name is fully qualified or the fqdn
		     option is set in sudoers(5))

		 %h  expanded to the local host name without the domain name

		 %p  expanded to the name of the user whose password is being
		     requested (respects the rootpw, targetpw, and runaspw
		     flags in sudoers(5))

		 %U  expanded to the login name of the user the command will
		     be run as (defaults to root unless the -u option is also

		 %u  expanded to the invoking user's login name

		 %%  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
		 to by the security policy) but does not run a command.	 Not
		 all security policies support cached credentials.

     --		 The -- option indicates that sudo should stop processing com-
		 mand line arguments.

     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 otherwise be forbidden.  See
     sudoers(5) for more information.

     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:

     o	 real and effective user ID

     o	 real and effective group ID

     o	 supplementary group IDs

     o	 the environment list

     o	 current working directory

     o	 file creation mode mask (umask)

     o	 SELinux role and type

     o	 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-
     system processes other than itself before rebooting the systyem.  This
     prevents sudo from relaying the SIGTERM signal it received back to
     reboot(8), which might then exit before the system was actually rebooted,
     leaving it in a half-dead state similar to single user mode.  Note, how-
     ever, that this check only applies to the command run by sudo and not any
     other processes that the command may create.  As a result, running a
     script that calls reboot(8) or shutdown(8) via sudo may cause the system
     to end up in this undefined state unless the reboot(8) or shutdown(8) are
     run using the exec() family of functions instead of system() (which
     interposes a shell between the command and the calling process).

     Plugins are dynamically loaded based on the contents of the
     /etc/sudo.conf file.  If no /etc/sudo.conf file is present, or it con-
     tains no Plugin lines, sudo will use the traditional sudoers security
     policy and I/O logging, which corresponds to the following /etc/sudo.conf

     # 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.

     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

     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-

     noexec    The fully-qualified path to a shared library containing dummy
	       versions of the execv(), execve() and fexecve() library func-
	       tions that just return an error.	 This is used to implement the
	       noexec functionality on systems that support LD_PRELOAD or its
	       equivalent.  Defaults to /usr/libexec/sudo_noexec.so.

     sudo versions 1.8.4 and higher support a flexible debugging framework
     that can help track down what sudo is doing internally if there is a

     A Debug line consists of the Debug keyword, followed by the name of the
     program to debug (sudo, visudo, sudoreplay), the debug file name and a
     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

     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 exits with a value of 1 if there is a configuration/per-
     mission problem or if sudo cannot execute the given command.  In the lat-
     ter case the error string is printed to the standard error.  If sudo can-
     not 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 auto-
     mounter and one of the directories in your PATH is on a machine that is
     currently unreachable.

     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.

     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_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 name of the user who invoked sudo.

     USER	      Set to the target user (root unless the -u option is

     VISUAL	      Default editor to use in -e (sudoedit) mode if
		      SUDO_EDITOR is not set.

     /etc/sudo.conf	       sudo front end configuration

     Note: the following examples assume a properly configured security pol-

     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"

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

     See the HISTORY file in the sudo distribution
     (http://www.sudo.ws/sudo/history.html) for a brief history of sudo.

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

	   Todd C. Miller

     See the CONTRIBUTORS file in the sudo distribution
     (http://www.sudo.ws/sudo/contributors.html) for an exhaustive list of
     people who have contributed to sudo.

     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).

     If you feel you have found a bug in sudo, please submit a bug report at

     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

     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