VISUDO(8) - phpMan

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, provides 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 envi-
               ronment variable if possible, or the first editor in the list that exists and is
               executable.  Note that the SUDO_EDITOR, VISUAL and EDITOR environment variables
               are not preserved by default when the env_reset sudoers option is enabled.  The
               default editor path is /usr/bin/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 cre-
               ate 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 edi-
               tors in the editor variable.  visudo will then only use SUDO_EDITOR, VISUAL or
               EDITOR if they match a value specified 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 function when visudo is
               invoked via sudo.  The default value is on, which can be set at compile time via
               the --with-env-editor configure 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,
                 /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 `-', indi-
                 cating 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 letters, 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 specified, 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
     /etc/sudo.conf            Sudo front end configuration

     /etc/sudoers              List of who can run what

     /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.

     /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
           underscore (`_') 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 message 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 pars-
           ing 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 pri-
     marily 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 lim-
     ited 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 complete details.

Sudo 1.8.23                              January 26, 2018                             Sudo 1.8.23