.\"
.\" Copyright (c) 1996,1998-2005, 2007-2015
.\" Todd C. Miller <Todd.Miller@courtesan.com>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" Sponsored in part by the Defense Advanced Research Projects
.\" Agency (DARPA) and Air Force Research Laboratory, Air Force
.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
.\"
.Dd November 20, 2015
.Dt VISUDO @mansectsu@
.Os Sudo @PACKAGE_VERSION@
.Sh NAME
.Nm visudo
.Nd edit the sudoers file
.Sh SYNOPSIS
.Nm visudo
.Op Fl chqsV
.Op Fl f Ar sudoers
.Op Fl x Ar output_file
.Sh DESCRIPTION
.Nm
edits the
.Em sudoers
file in a safe fashion, analogous to
.Xr vipw @mansectsu@ .
.Nm
locks the
.Em sudoers
file against multiple simultaneous edits, provides basic sanity checks,
and checks for parse errors.
If the
.Em sudoers
file is currently being edited you will receive a message to try again later.
.Pp
There is a hard-coded list of one or more editors that
.Nm
will use set at compile-time that may be overridden via the
.Em editor
.Em sudoers
.Li Default
variable.
This list defaults to
.Li "@editor@" .
Normally,
.Nm
does not honor the
.Ev VISUAL
or
.Ev EDITOR
environment variables unless they contain an editor in the aforementioned
editors list.
However, if
.Nm
is configured with the
.Li --with-env-editor
option or the
.Em env_editor
.Li Default
variable is set in
.Em sudoers ,
.Nm
will use any the editor defines by
.Ev VISUAL
or
.Ev EDITOR .
Note that this can be a security hole since it allows the user to
execute any program they wish simply by setting
.Ev VISUAL
or
.Ev EDITOR .
.Pp
.Nm
parses the
.Em sudoers
file after the edit and will
not save the changes if there is a syntax error.
Upon finding an error,
.Nm
will print a message stating the line number(s)
where the error occurred and the user will receive the
.Dq What now?
prompt.
At this point the user may enter
.Ql e
to re-edit the
.Em sudoers
file,
.Ql x
to exit without saving the changes, or
.Ql Q
to quit and save changes.
The
.Ql Q
option should be used with extreme care because if
.Nm
believes there to be a parse error, so will
.Nm sudo
and no one
will be able to run
.Nm sudo
again until the error is fixed.
If
.Ql e
is typed to edit the
.Em 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).
.Pp
The options are as follows:
.Bl -tag -width Fl
.It Fl c , -check
Enable
.Em check-only
mode.
The existing
.Em sudoers
file will be
checked for syntax errors, owner and mode.
A message will be printed to the standard output describing the status of
.Em sudoers
unless the
.Fl q
option was specified.
If the check completes successfully,
.Nm
will exit with a value of 0.
If an error is encountered,
.Nm
will exit with a value of 1.
.It Fl f Ar sudoers , Fl -file Ns = Ns Ar sudoers
Specify an alternate
.Em sudoers
file location.
With this option,
.Nm
will edit (or check) the
.Em sudoers
file of your choice,
instead of the default,
.Pa @sysconfdir@/sudoers .
The lock file used is the specified
.Em sudoers
file with
.Dq \.tmp
appended to it.
In
.Em check-only
mode only, the argument to
.Fl f
may be
.Ql - ,
indicating that
.Em sudoers
will be read from the standard input.
.It Fl h , -help
Display a short help message to the standard output and exit.
.It Fl q , -quiet
Enable
.Em quiet
mode.
In this mode details about syntax errors are not printed.
This option is only useful when combined with
the
.Fl c
option.
.It Fl s , -strict
Enable
.Em strict
checking of the
.Em sudoers
file.
If an alias is used before it is defined,
.Nm
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
.Pq Ql _
character.
.It Fl V , -version
Print the
.Nm
and
.Em sudoers
grammar versions and exit.
.It Fl x Ar output_file , Fl -export Ns = Ns Ar output_file
Export a
.Em sudoers
in JSON format and write it to
.Ar output_file .
If
.Ar output_file
is
.Ql - ,
the exported
.Em sudoers
policy will be written to the standard output.
By default,
.Pa @sysconfdir@/sudoers
(and any files it includes) will be exported.
The
.Fl f
option can be used to specify a different
.Em sudoers
file to export.
The exported format is intended to be easier for third-party
applications to parse than the traditional
.Em sudoers
format.
The various values have explicit types which removes much of the
ambiguity of the
.Em sudoers
format.
.El
.Ss Debugging and sudoers plugin arguments
.Nm
versions 1.8.4 and higher support a flexible debugging framework
that is configured via
.Li Debug
lines in the
.Xr sudo.conf @mansectform@
file.
.Pp
Starting with
.Nm sudo
1.8.12,
.Nm
will also parse the arguments to the
.Em sudoers
plugin to override the default
.Em sudoers
path name, UID, GID and file mode.
These arguments, if present, should be listed after the path to the plugin
(i.e.\& after
.Pa sudoers.so ) .
Multiple arguments may be specified, separated by white space.
For example:
.Bd -literal -offset indent
Plugin sudoers_policy sudoers.so sudoers_mode=0400
.Ed
.Pp
The following arguments are supported:
.Bl -tag -width 8n
.It sudoers_file=pathname
The
.Em sudoers_file
argument can be used to override the default path to the
.Em sudoers
file.
.It sudoers_uid=uid
The
.Em sudoers_uid
argument can be used to override the default owner of the sudoers file.
It should be specified as a numeric user ID.
.It sudoers_gid=gid
The
.Em 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).
.It sudoers_mode=mode
The
.Em sudoers_mode
argument can be used to override the default file mode for the sudoers file.
It should be specified as an octal value.
.El
.Pp
For more information on configuring
.Xr sudo.conf @mansectform@ ,
please refer to its manual.
.Sh ENVIRONMENT
The following environment variables may be consulted depending on
the value of the
.Em editor
and
.Em env_editor
.Em sudoers
settings:
.Bl -tag -width 15n
.It Ev VISUAL
Invoked by
.Nm
as the editor to use
.It Ev EDITOR
Used by
.Nm
if
.Ev VISUAL
is not set
.El
.Sh FILES
.Bl -tag -width 24n
.It Pa @sysconfdir@/sudo.conf
Sudo front end configuration
.It Pa @sysconfdir@/sudoers
List of who can run what
.It Pa @sysconfdir@/sudoers.tmp
Lock file for visudo
.El
.Sh DIAGNOSTICS
.Bl -tag -width 4n
.It Li sudoers file busy, try again later.
Someone else is currently editing the
.Em sudoers
file.
.It Li @sysconfdir@/sudoers.tmp: Permission denied
You didn't run
.Nm
as root.
.It Li Can't find you in the passwd database
Your user ID does not appear in the system passwd file.
.It Li 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
.Pq Ql _
character.
In the latter case, you can ignore the warnings
.Po
.Nm sudo
will not complain
.Pc .
In
.Fl s
(strict) mode these are errors, not warnings.
.It Li Warning: unused {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias was defined but never
used.
You may wish to comment out or remove the unused alias.
.It Li 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.
This is only a warning by default as
.Nm sudo
will ignore cycles when parsing
the
.Em sudoers
file.
.It Li visudo: @sysconfdir@/sudoers: input and output files must be different
The
.Fl x
flag was used and the specified
.Ar output_file
has the same path name as the
.Em sudoers
file to export.
.El
.Sh SEE ALSO
.Xr vi 1 ,
.Xr sudo.conf @mansectform@ ,
.Xr sudoers @mansectform@ ,
.Xr sudo @mansectsu@ ,
.Xr vipw @mansectsu@
.Sh AUTHORS
Many people have worked on
.Nm sudo
over the years; this version consists of code written primarily by:
.Bd -ragged -offset indent
.An Todd C. Miller
.Ed
.Pp
See the CONTRIBUTORS file in the
.Nm sudo
distribution (https://www.sudo.ws/contributors.html) for an
exhaustive list of people who have contributed to
.Nm sudo .
.Sh CAVEATS
There is no easy way to prevent a user from gaining a root shell if
the editor used by
.Nm
allows shell escapes.
.Sh BUGS
If you feel you have found a bug in
.Nm ,
please submit a bug report at https://bugzilla.sudo.ws/
.Sh 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.
.Sh DISCLAIMER
.Nm
is provided
.Dq 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
.Nm sudo
or https://www.sudo.ws/license.html for complete details.