Attachment #120352 for bug #163149

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sudo(8) 		     MAINTENANCE COMMANDS		       sudo(8)

<a name="NAME" href="#end"><b>NAME</b></a>
       sudo - execute a command as another user

<a name="SYNOPSIS" href="#end"><b>SYNOPSIS</b></a>
       <b>sudo</b> <b>-V</b> | <b>-h</b> | <b>-l</b> | <b>-L</b> | <b>-v</b> | <b>-k</b> | <b>-K</b> | <b>-s</b> | [ <b>-H</b> ] [<b>-P</b> ] [<b>-S</b> ] [ <b>-b</b> ]
       | [ <b>-p</b> <i>prompt</i> ] [ <b>-c</b> <i>class</i>|<i>-</i> ] [ <b>-a</b> <i>auth</i><b>_</b><i>type</i> ] [ <b>-u</b> <i>username</i>|<i>#uid</i> ]
       <i>command</i>

<a name="DESCRIPTION" href="#end"><b>DESCRIPTION</b></a>
       <b>sudo</b> allows a permitted user to execute a <i>command</i> as the superuser or
       another user, as specified in the <i>sudoers</i> file.	The real and effective
       uid and gid are set to match those of the target user as specified in
       the passwd file (the group vector is also initialized when the target
       user is not root).  By default, <b>sudo</b> requires that users authenticate
       themselves with a password (NOTE: by default this is the user's pass-
       word, 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 <i>sudoers</i>).

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

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

       <b>sudo</b> can log both successful and unsuccessful attempts (as well as
       errors) to <a href="/cgi/man.cgi?query=syslog&amp;sektion=3&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>syslog</i>(3)</a>, a log file, or both.  By default <b>sudo</b> will log
       via <a href="/cgi/man.cgi?query=syslog&amp;sektion=3&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>syslog</i>(3)</a> but this is changeable at configure time or via the <i>sudo-</i>
       <i>ers</i> file.

<a name="OPTIONS" href="#end"><b>OPTIONS</b></a>
       <b>sudo</b> accepts the following command line options:

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

       -l  The <b>-l</b> (<i>list</i>) option will list out the allowed (and forbidden) com-
	   mands for the user on the current host.

       -L  The <b>-L</b> (<i>list</i> defaults) option will list out the parameters that may
	   be set in a <i>Defaults</i> line along with a short description for each.
	   This option is useful in conjunction with <a href="/cgi/man.cgi?query=grep&amp;sektion=1&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>grep</i>(1)</a>.

       -h  The <b>-h</b> (<i>help</i>) option causes <b>sudo</b> to print a usage message and exit.

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

       -k  The <b>-k</b> (<i>kill</i>) option to <b>sudo</b> invalidates the user's timestamp by
	   setting the time on it to the epoch.  The next time <b>sudo</b> is run a
	   password will be required.  This option does not require a password
	   and was added to allow a user to revoke <b>sudo</b> permissions from a
	   .logout file.

       -K  The <b>-K</b> (sure <i>kill</i>) option to <b>sudo</b> removes the user's timestamp
	   entirely.  Likewise, this option does not require a password.

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

       -p  The <b>-p</b> (<i>prompt</i>) option allows you to override the default password
	   prompt and use a custom one.  If the password prompt contains the
	   %u escape, %u will be replaced with the user's login name.  Simi-
	   larly, %h will be replaced with the local hostname.

       -c  The <b>-c</b> (<i>class</i>) option causes <b>sudo</b> to run the specified command with
	   resources limited by the specified login class.  The <i>class</i> argument
	   can be either a class name as defined in /etc/login.conf, or a sin-
	   gle '-' character.  Specifying a <i>class</i> of - indicates that the com-
	   mand should be run restricted by the default login capabilities for
	   the user the command is run as.  If the <i>class</i> argument specifies an
	   existing user class, the command must be run as root, or the <b>sudo</b>
	   command must be run from a shell that is already root.  This option
	   is only available on systems with BSD login classes where <b>sudo</b> has
	   been configured with the --with-logincap option.

       -a  The <b>-a</b> (<i>authentication</i> <i>type</i>) option causes <b>sudo</b> to use the speci-
	   fied authentication type when validating the user, as allowed by
	   /etc/login.conf.  The system administrator may specify a list of
	   sudo-specific authentication methods by adding an "auth-sudo" entry
	   in /etc/login.conf.	This option is only available on systems that
	   support BSD authentication where <b>sudo</b> has been configured with the
	   --with-bsdauth option.

       -u  The <b>-u</b> (<i>user</i>) option causes <b>sudo</b> to run the specified command as a
	   user other than <i>root</i>.  To specify a <i>uid</i> instead of a <i>username</i>, use
	   <i>#uid</i>.

       -s  The <b>-s</b> (<i>shell</i>) option runs the shell specified by the <i>SHELL</i> envi-
	   ronment variable if it is set or the shell as specified in
	   <a href="/cgi/man.cgi?query=passwd&amp;sektion=5&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>passwd</i>(5)</a>.

       -H  The <b>-H</b> (<i>HOME</i>) option sets the HOME environment variable to the
	   homedir of the target user (root by default) as specified in
	   <a href="/cgi/man.cgi?query=passwd&amp;sektion=5&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>passwd</i>(5)</a>.  By default, <b>sudo</b> does not modify HOME.

       -P  The <b>-P</b> (<i>preserve</i> <i>group</i> <i>vector</i>) option causes <b>sudo</b> to preserve the
	   user's group vector unaltered.  By default, <b>sudo</b> 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.

       -S  The <b>-S</b> (<i>stdin</i>) option causes <b>sudo</b> to read the password from stan-
	   dard input instead of the terminal device.

       --  The <b>--</b> flag indicates that <b>sudo</b> should stop processing command line
	   arguments.  It is most useful in conjunction with the <b>-s</b> flag.

<a name="RETURN VALUES" href="#end"><b>RETURN VALUES</b></a>
       Upon successful execution of a program, the return value from <b>sudo</b> will
       simply be the return value of the program that was executed.

       Otherwise, <b>sudo</b> quits with an exit value of 1 if there is a configura-
       tion/permission problem or if <b>sudo</b> cannot execute the given command.
       In the latter case the error string is printed to stderr.  If <b>sudo</b> can-
       not <a href="/cgi/man.cgi?query=stat&amp;sektion=2&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>stat</i>(2)</a> 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

       mounter and one of the directories in your PATH is on a machine that is
       currently unreachable.

<a name="SECURITY NOTES" href="#end"><b>SECURITY NOTES</b></a>
       <b>sudo</b> tries to be safe when executing external commands.	Variables that
       control how dynamic loading and binding is done can be used to subvert
       the program that <b>sudo</b> runs.  To combat this the LD_*, _RLD_*,
       SHLIB_PATH (HP-UX only), and LIBPATH (AIX only) environment variables
       are removed from the environment passed on to all commands executed.
       <b>sudo</b> will also remove the IFS, ENV, BASH_ENV, KRB_CONF, KRBCONFDIR,
       KRBTKFILE, KRB5_CONFIG, LOCALDOMAIN, RES_OPTIONS, HOSTALIASES, NLSPATH,
       PATH_LOCALE, TERMINFO, TERMINFO_DIRS and TERMPATH variables as they too
       can pose a threat.  If the TERMCAP variable is set and is a pathname,
       it too is ignored.  Additionally, if the LC_* or LANGUAGE variables
       contain the / or % characters, they are ignored.  If <b>sudo</b> has been com-
       piled with SecurID support, the VAR_ACE, USR_ACE and DLC_ACE variables
       are cleared as well.  The list of environment variables that <b>sudo</b>
       clears is contained in the output of sudo -V when run as root.

       To prevent command spoofing, <b>sudo</b> 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
       environment variable is <i>not</i> modified and is passed unchanged to the
       program that <b>sudo</b> executes.

       For security reasons, if your OS supports shared libraries and does not
       disable user-defined library search paths for setuid programs (most
       do), you should either use a linker option that disables this behavior
       or link <b>sudo</b> statically.

       <b>sudo</b> will check the ownership of its timestamp directory (<i>/var/run/sudo</i>
       by default) and ignore the directory's contents if it is not owned by
       root and only writable by root.	On systems that allow non-root users
       to give away files via <a href="/cgi/man.cgi?query=chown&amp;sektion=2&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>chown</i>(2)</a>, if the timestamp directory is located
       in a directory writable by anyone (e.g.: <i>/tmp</i>), it is possible for a
       user to create the timestamp directory before <b>sudo</b> is run.  However,
       because <b>sudo</b> 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

       <i>/var/run/sudo</i> with the appropriate owner (root) and permissions (0700)
       in the system startup files.

       <b>sudo</b> 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 <b>sudo</b> will 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 <i>not</i> be logged, nor will <b>sudo</b>'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 <b>sudo</b> to verify that the command
       does not inadvertantly give the user an effective root shell.

<a name="EXAMPLES" href="#end"><b>EXAMPLES</b></a>
       Note: the following examples assume suitable <a href="/cgi/man.cgi?query=sudoers&amp;sektion=5&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>sudoers</i>(5)</a> entries.

       To get a file listing of an unreadable directory:


	% sudo sh -c "cd /home ; du -s * | sort -rn &gt; USAGE"

<a name="ENVIRONMENT" href="#end"><b>ENVIRONMENT</b></a>
       <b>sudo</b> utilizes the following environment variables:

	PATH		       Set to a sane value if SECURE_PATH is set
	SHELL		       Used to determine shell to run with -s option

	SUDO_GID	       Set to the gid of the user who invoked sudo
	SUDO_PS1	       If set, PS1 will be set to its value

<a name="FILES" href="#end"><b>FILES</b></a>
	/etc/sudoers	       List of who can run what
	/var/run/sudo		   Directory containing timestamps

<a name="AUTHORS" href="#end"><b>AUTHORS</b></a>
       Many people have worked on <b>sudo</b> over the years; this version consists
       of code written primarily by:

	       Todd Miller
	       Chris Jepeway

       See the HISTORY file in the <b>sudo</b> distribution or visit
       <a href="http://www.sudo.ws/sudo/history.html">http://www.sudo.ws/sudo/history.html</a> for a short history of <b>sudo</b>.

<a name="BUGS" href="#end"><b>BUGS</b></a>
       If you feel you have found a bug in sudo, please submit a bug report at
       <a href="http://www.sudo.ws/sudo/bugs/">http://www.sudo.ws/sudo/bugs/</a>

<a name="DISCLAIMER" href="#end"><b>DISCLAIMER</b></a>
       <b>Sudo</b> is provided ``AS IS'' and any express or implied warranties,
       including, but not limited to, the implied warranties of merchantabil-
       ity and fitness for a particular purpose are disclaimed.  See the
       LICENSE file distributed with <b>sudo</b> for complete details.

<a name="CAVEATS" href="#end"><b>CAVEATS</b></a>
       There is no easy way to prevent a user from gaining a root shell if
       that user has access to commands allowing shell escapes.


       their own program that gives them a root shell regardless of any '!'
       elements in the user specification.

       Running shell scripts via <b>sudo</b> can expose the same kernel bugs that
       make setuid shell scripts unsafe on some operating systems (if your OS
       supports the /dev/fd/ directory, setuid shell scripts are generally
       safe).

<a name="SEE_ALSO" href="#end"><b>SEE_ALSO</b></a>
       <a href="/cgi/man.cgi?query=stat&amp;sektion=2&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>stat</i>(2)</a>, <i>login</i><b>_</b><a href="/cgi/man.cgi?query=cap&amp;sektion=3&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>cap</i>(3)</a>, <a href="/cgi/man.cgi?query=sudoers&amp;sektion=5&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>sudoers</i>(5)</a>, <a href="/cgi/man.cgi?query=passwd&amp;sektion=5&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>passwd</i>(5)</a>, <a href="/cgi/man.cgi?query=visudo&amp;sektion=8&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>visudo</i>(8)</a>, <a href="/cgi/man.cgi?query=grep&amp;sektion=1&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>grep</i>(1)</a>,
       <a href="/cgi/man.cgi?query=su&amp;sektion=1&amp;apropos=0&amp;manpath=Red+Hat+Linux%2fi386+9"><i>su</i>(1)</a>.


</pre>
<a name="end" />
<hr />
<a href="#NAME">NAME</a> |
<a href="#SYNOPSIS">SYNOPSIS</a> |
<a href="#DESCRIPTION">DESCRIPTION</a> |
<a href="#OPTIONS">OPTIONS</a> |
<a href="#RETURN_VALUES">RETURN VALUES</a> |
<a href="#SECURITY_NOTES">SECURITY NOTES</a> |
<a href="#ENVIRONMENT">ENVIRONMENT</a> |
<a href="#FILES">FILES</a> |
<a href="#EXAMPLES">EXAMPLES</a> |
<a href="#SEE_ALSO">SEE ALSO</a> |
<a href="#AUTHORS">AUTHORS</a> |
<a href="#CAVEATS">CAVEATS</a> |
<a href="#BUGS">BUGS</a> |
<a href="#SUPPORT">SUPPORT</a> |
<a href="#DISCLAIMER">DISCLAIMER</a>
<p align="left">Want to link to this manual page? Use this URL:<br/>&lt;<a href="http://www.freebsd.org/cgi/man.cgi?query=sudo&amp;manpath=Red+Hat+Linux%2fi386+9">http://www.freebsd.org/cgi/man.cgi?query=sudo&amp;manpath=Red+Hat+Linux%2fi386+9</a>&gt;</p>
<a href="/cgi/man.cgi?manpath=">home</a> | <a href="/cgi/man.cgi/help.html">help</a> 
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