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Copyright (c) 1996,1998-2005, 2007-2012
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Todd C. Miller <Todd.Miller@courtesan.com>
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Permission to use, copy, modify, and distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Sponsored in part by the Defense Advanced Research Projects
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Agency (DARPA) and Air Force Research Laboratory, Air Force
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Materiel Command, USAF, under agreement number F39502-99-1-0512.
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visudo - edit the sudoers file
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B<visudo> [B<-chqsV>] [B<-f> I<sudoers>]
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B<visudo> edits the I<sudoers> file in a safe fashion, analogous to
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L<vipw(8)>. B<visudo> locks the I<sudoers> file against multiple
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simultaneous edits, provides basic sanity checks, and checks
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for parse errors. If the I<sudoers> file is currently being
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edited you will receive a message to try again later.
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There is a hard-coded list of one or more editors that B<visudo> will
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use set at compile-time that may be overridden via the I<editor> I<sudoers>
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C<Default> variable. This list defaults to C<"@editor@">. Normally,
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B<visudo> does not honor the C<VISUAL> or C<EDITOR> environment
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variables unless they contain an editor in the aforementioned editors
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list. However, if B<visudo> is configured with the I<--with-env-editor>
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option or the I<env_editor> C<Default> variable is set in I<sudoers>,
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B<visudo> will use any the editor defines by C<VISUAL> or C<EDITOR>.
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Note that this can be a security hole since it allows the user to
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execute any program they wish simply by setting C<VISUAL> or C<EDITOR>.
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B<visudo> parses the I<sudoers> file after the edit and will
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not save the changes if there is a syntax error. Upon finding
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an error, B<visudo> will print a message stating the line number(s)
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where the error occurred and the user will receive the
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"What now?" prompt. At this point the user may enter "e"
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to re-edit the I<sudoers> file, "x" to exit without
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saving the changes, or "Q" to quit and save changes. The
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"Q" option should be used with extreme care because if B<visudo>
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believes there to be a parse error, so will B<sudo> and no one
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will be able to B<sudo> again until the error is fixed.
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If "e" is typed to edit the I<sudoers> file after a parse error
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has been detected, the cursor will be placed on the line where the
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error occurred (if the editor supports this feature).
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B<visudo> accepts the following command line options:
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Enable B<check-only> mode. The existing I<sudoers> file will be
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checked for syntax errors, owner and mode. A message will be printed
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to the standard output describing the status of I<sudoers> unless
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the B<-q> option was specified. If the check completes successfully,
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B<visudo> will exit with a value of 0. If an error is encountered,
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B<visudo> will exit with a value of 1.
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Specify and alternate I<sudoers> file location. With this option
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B<visudo> will edit (or check) the I<sudoers> file of your choice,
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instead of the default, F<@sysconfdir@/sudoers>. The lock file used
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is the specified I<sudoers> file with ".tmp" appended to it.
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In B<check-only> mode only, the argument to B<-f> may be "-",
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indicating that I<sudoers> will be read from the standard input.
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The B<-h> (I<help>) option causes B<visudo> to print a short help message
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to the standard output and exit.
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Enable B<quiet> mode. In this mode details about syntax errors
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are not printed. This option is only useful when combined with
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Enable B<strict> checking of the I<sudoers> file. If an alias is
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used before it is defined, B<visudo> will consider this a parse
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error. Note that it is not possible to differentiate between an
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alias and a host name or user name that consists solely of uppercase
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letters, digits, and the underscore ('_') character.
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The B<-V> (version) option causes B<visudo> to print its version number
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The following environment variables may be consulted depending on
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the value of the I<editor> and I<env_editor> I<sudoers> variables:
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Invoked by visudo as the editor to use
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Used by visudo if VISUAL is not set
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=item F<@sysconfdir@/sudoers>
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List of who can run what
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=item F<@sysconfdir@/sudoers.tmp>
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=item sudoers file busy, try again later.
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Someone else is currently editing the I<sudoers> file.
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=item @sysconfdir@/sudoers.tmp: Permission denied
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You didn't run B<visudo> as root.
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=item Can't find you in the passwd database
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Your userid does not appear in the system passwd file.
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=item Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
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Either you are trying to use an undeclare {User,Runas,Host,Cmnd}_Alias
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or you have a user or host name listed that consists solely of
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uppercase letters, digits, and the underscore ('_') character. In
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the latter case, you can ignore the warnings (B<sudo> will not
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complain). In B<-s> (strict) mode these are errors, not warnings.
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=item Warning: unused {User,Runas,Host,Cmnd}_Alias
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The specified {User,Runas,Host,Cmnd}_Alias was defined but never
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used. You may wish to comment out or remove the unused alias. In
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B<-s> (strict) mode this is an error, not a warning.
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=item Warning: cycle in {User,Runas,Host,Cmnd}_Alias
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The specified {User,Runas,Host,Cmnd}_Alias includes a reference to
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itself, either directly or through an alias it includes. This is
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only a warning by default as B<sudo> will ignore cycles when parsing
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L<vi(1)>, L<sudoers(5)>, L<sudo(8)>, L<vipw(8)>
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Many people have worked on B<sudo> over the years; this version of
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B<visudo> was written by:
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See the CONTRIBUTORS file in the B<sudo> distribution
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(http://www.sudo.ws/sudo/contributors.html) for a list of people
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who have contributed to B<sudo>.
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There is no easy way to prevent a user from gaining a root shell if
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the editor used by B<visudo> allows shell escapes.
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If you feel you have found a bug in B<visudo>, please submit a bug report
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at http://www.sudo.ws/sudo/bugs/
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Limited free support is available via the sudo-users mailing list,
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see http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or
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B<visudo> is provided ``AS IS'' and any express or implied warranties,
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including, but not limited to, the implied warranties of merchantability
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and fitness for a particular purpose are disclaimed. See the LICENSE
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file distributed with B<sudo> or http://www.sudo.ws/sudo/license.html
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for complete details.
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doc/visudo.pod
