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


NAME

     visudo -- edit the sudoers file


SYNOPSIS

     visudo [-chqsV] [-f sudoers]


DESCRIPTION

     visudo edits the sudoers file in a safe fashion, analogous to vipw(8).
     visudo locks the sudoers file against multiple simultaneous edits, pro-
     vides basic sanity checks, and checks for parse errors.  If the sudoers
     file is currently being edited you will receive a message to try again
     later.

     visudo parses the sudoers file after editing and will not save the
     changes if there is a syntax error.  Upon finding an error, visudo will
     print a message stating the line number(s) where the error occurred and
     the user will receive the ``What now?'' prompt.  At this point the user
     may enter `e' to re-edit the sudoers file, `x' to exit without saving the
     changes, or `Q' to quit and save changes.  The `Q' option should be used
     with extreme caution because if visudo believes there to be a parse
     error, so will sudo and no one will be able to run sudo again until the
     error is fixed.  If `e' is typed to edit the sudoers file after a parse
     error has been detected, the cursor will be placed on the line where the
     error occurred (if the editor supports this feature).

     There are two sudoers settings that determine which editor visudo will
     run.

     editor    A colon (`:') separated list of editors allowed to be used with
               visudo.  visudo will choose the editor that matches the user's
               SUDO_EDITOR, VISUAL or EDITOR environment variable if possible,
               or the first editor in the list that exists and is executable.
               Note that the SUDO_EDITOR, VISUAL and EDITOR environment vari-
               ables are not preserved by default when the env_reset sudoers
               option is enabled.  The default editor path is vi which can be
               set at compile time via the --with-editor configure option.

     env_editor
               If set, visudo will use the value of the SUDO_EDITOR, VISUAL or
               EDITOR environment variables before falling back on the default
               editor list.  Note that this may create a security hole as it
               allows the user to run any arbitrary command as root without
               logging.  A safer alternative is to place a colon-separated
               list of editors in the editor variable.  visudo will then only
               use SUDO_EDITOR, VISUAL or EDITOR if they match a value speci-
               fied in editor.  If the env_reset flag is enabled, the
               SUDO_EDITOR, VISUAL and/or EDITOR environment variables must be
               present in the env_keep list for the env_editor flag to func-
               tion when visudo is invoked via sudo.  The default value is on,
               which can be set at compile time via the --with-env-editor con-
               figure option.

     The options are as follows:

     -c, --check
                 Enable check-only mode.  The existing sudoers file (and any
                 other files it includes) will be checked for syntax errors.
                 If the -f option has not been specified, visudo will also
                 check the sudoers file owner and mode.  A message will be
                 printed to the standard output describing the status of
                 sudoers unless the -q option was specified.  If the check
                 completes successfully, visudo will exit with a value of 0.
                 If an error is encountered, visudo will exit with a value of
                 1.

     -f sudoers, --file=sudoers
                 Specify an alternate sudoers file location.  With this
                 option, visudo will edit (or check) the sudoers file of your
                 choice, instead of the default, /opt/local/etc/sudoers.  The
                 lock file used is the specified sudoers file with ``.tmp''
                 appended to it.  In check-only mode only, the argument to -f
                 may be `-', indicating that sudoers will be read from the
                 standard input.  Because the policy is evaluated in its
                 entirety, it is not sufficient to check an individual sudoers
                 include file for syntax errors.

     -h, --help  Display a short help message to the standard output and exit.

     -q, --quiet
                 Enable quiet mode.  In this mode details about syntax errors
                 are not printed.  This option is only useful when combined
                 with the -c option.

     -s, --strict
                 Enable strict checking of the sudoers file.  If an alias is
                 referenced but not actually defined or if there is a cycle in
                 an alias, visudo will consider this a parse error.  Note that
                 it is not possible to differentiate between an alias and a
                 host name or user name that consists solely of uppercase let-
                 ters, digits, and the underscore (`_') character.

     -V, --version
                 Print the visudo and sudoers grammar versions and exit.

   Debugging and sudoers plugin arguments
     visudo versions 1.8.4 and higher support a flexible debugging framework
     that is configured via Debug lines in the sudo.conf(5) file.

     Starting with sudo 1.8.12, visudo will also parse the arguments to the
     sudoers plugin to override the default sudoers path name, UID, GID and
     file mode.  These arguments, if present, should be listed after the path
     to the plugin (i.e. after sudoers.so).  Multiple arguments may be speci-
     fied, separated by white space.  For example:

           Plugin sudoers_policy sudoers.so sudoers_mode=0400

     The following arguments are supported:

     sudoers_file=pathname
               The sudoers_file argument can be used to override the default
               path to the sudoers file.

     sudoers_uid=uid
               The sudoers_uid argument can be used to override the default
               owner of the sudoers file.  It should be specified as a numeric
               user ID.

     sudoers_gid=gid
               The sudoers_gid argument can be used to override the default
               group of the sudoers file.  It must be specified as a numeric
               group ID (not a group name).

     sudoers_mode=mode
               The sudoers_mode argument can be used to override the default
               file mode for the sudoers file.  It should be specified as an
               octal value.

     For more information on configuring sudo.conf(5), please refer to its
     manual.


ENVIRONMENT

     The following environment variables may be consulted depending on the
     value of the editor and env_editor sudoers settings:

     SUDO_EDITOR      Invoked by visudo as the editor to use

     VISUAL           Used by visudo if SUDO_EDITOR is not set

     EDITOR           Used by visudo if neither SUDO_EDITOR nor VISUAL is set


FILES

     /opt/local/etc/sudo.conf  Sudo front end configuration

     /opt/local/etc/sudoers    List of who can run what

     /opt/local/etc/sudoers.tmp
                               Lock file for visudo


DIAGNOSTICS

     In addition to reporting sudoers parse errors, visudo may produce the
     following messages:

     sudoers file busy, try again later.
           Someone else is currently editing the sudoers file.

     /opt/local/etc/sudoers.tmp: Permission denied
           You didn't run visudo as root.

     you do not exist in the passwd database
           Your user ID does not appear in the system passwd database.

     Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
           Either you are trying to use an undeclared
           {User,Runas,Host,Cmnd}_Alias or you have a user or host name listed
           that consists solely of uppercase letters, digits, and the under-
           score (`_') character.  In the latter case, you can ignore the
           warnings (sudo will not complain).  The message is prefixed with
           the path name of the sudoers file and the line number where the
           undefined alias was used.  In -s (strict) mode these are errors,
           not warnings.

     Warning: unused {User,Runas,Host,Cmnd}_Alias
           The specified {User,Runas,Host,Cmnd}_Alias was defined but never
           used.  The message is prefixed with the path name of the sudoers
           file and the line number where the unused alias was defined.  You
           may wish to comment out or remove the unused alias.

     Warning: cycle in {User,Runas,Host,Cmnd}_Alias
           The specified {User,Runas,Host,Cmnd}_Alias includes a reference to
           itself, either directly or through an alias it includes.  The mes-
           sage is prefixed with the path name of the sudoers file and the
           line number where the cycle was detected.  This is only a warning
           unless visudo is run in -s (strict) mode as sudo will ignore cycles
           when parsing the sudoers file.

     unknown defaults entry "name"
           The sudoers file contains a Defaults setting not recognized by
           visudo.


SEE ALSO

     vi(1), sudo.conf(5), sudoers(5), sudo(8), vipw(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
     (https://www.sudo.ws/contributors.html) for an exhaustive list of people
     who have contributed to sudo.


CAVEATS

     There is no easy way to prevent a user from gaining a root shell if the
     editor used by visudo allows shell escapes.


BUGS

     If you feel you have found a bug in visudo, please submit a bug report at
     https://bugzilla.sudo.ws/


SUPPORT

     Limited free support is available via the sudo-users mailing list, see
     https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
     the archives.


DISCLAIMER

     visudo 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 https://www.sudo.ws/license.html for com-
     plete details.

Sudo 1.8.24                    January 26, 2018                    Sudo 1.8.24

sudo 1.8.24 - Generated Sun Aug 19 13:19:45 CDT 2018
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