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sudo(8)                      MAINTENANCE COMMANDS                      sudo(8)




NAME

       sudo, sudoedit - execute a command as another user


SYNOPSIS

       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]
       [-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.  The real and
       effective uid and gid are set to match those of the target user, as
       specified in the password database, and the group vector is initialized
       based on the group database (unless the -P option was specified).

       sudo supports a plugin architecture for security policies and
       input/output logging.  Third parties can develop and distribute their
       own policy and I/O logging modules 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
       unlimited.

       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.


OPTIONS

       sudo accepts the following command line options:

       -A          Normally, if sudo requires a password, it will read it from
                   the user's 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, if /etc/sudo.conf contains a
                   line specifying the askpass program, 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
                   error.

       -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.  Most interactive commands will fail to work
                   properly in background 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).  Values 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
                   security 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 policy, 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.

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

       -i [command]
                   The -i (simulate initial login) option runs the shell
                   specified 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
                   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.  Not all security policies
                   support credential 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 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, 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 specified)

                   %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.

       -S          The -S (stdin) option causes sudo to read the password from
                   the standard input instead of the terminal device.  The
                   password 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.

       -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' privileges.  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, use #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 in sudoers) but does not run a
                   command.  Not all security policies support cached
                   credentials.

       --          The -- option indicates that sudo should stop processing
                   command 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.


PLUGINS

       Plugins are dynamically loaded based on the contents of the
       /etc/sudo.conf file.  If no /etc/sudo.conf file is present, or it
       contains 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/local/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/local/libexec directory.  Any additional 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/local/libexec/sudo_noexec.dylib
        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 variable.

       noexec          The fully-qualified path to a shared library containing
                       dummy versions of the execv(), execve() and fexecve()
                       library functions 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/local/libexec/sudo_noexec.dylib.


DEBUG FLAGS

       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
       problem.

       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 command
       ,.

       For instance:

        Debug sudo /var/log/sudo_debug all@warn,plugin@info

       would log all debugging statements at the warn level and higher in
       addition 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
       severity, 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 sudo:

       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


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 exits with a 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 the
       standard error.  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.

       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.

       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 inadvertently 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
       disables 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.

        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 coreadm command can be used.


ENVIRONMENT

       sudo utilizes the following environment variables.  The security policy
       has control over the 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 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
       policy.

       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), sudo_plugin(8),
       sudo(8)


AUTHORS

       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 a list of people who
       have contributed to sudo.


HISTORY

       See the HISTORY file in the sudo distribution
       (http://www.sudo.ws/sudo/history.html) for a brief 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 the sudoers(5) module'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,
       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.



1.8.5                           March 15, 2012                         sudo(8)

sudo 1.8.5 - Generated Thu May 17 14:50:10 CDT 2012