path: root/doc/visudo.man.in

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.\" Copyright (c) 1996,1998-2005, 2007-2018
.\"	Todd C. Miller <Todd.Miller@sudo.ws>
.\"
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.\" Sponsored in part by the Defense Advanced Research Projects
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.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
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.TH "VISUDO" "@mansectsu@" "December 24, 2018" "Sudo @PACKAGE_VERSION@" "System Manager's Manual"
.nh
.if n .ad l
.SH "NAME"
\fBvisudo\fR
\- edit the sudoers file
.SH "SYNOPSIS"
.HP 7n
\fBvisudo\fR
[\fB\-chqsV\fR]
[[\fB\-f\fR]\ \fIsudoers\fR]
.SH "DESCRIPTION"
\fBvisudo\fR
edits the
\fIsudoers\fR
file in a safe fashion, analogous to
vipw(@mansectsu@).
\fBvisudo\fR
locks the
\fIsudoers\fR
file against multiple simultaneous edits, provides basic sanity checks,
and checks for parse errors.
If the
\fIsudoers\fR
file is currently being edited you will receive a message to try again later.
.PP
\fBvisudo\fR
parses the
\fIsudoers\fR
file after editing and will not save the changes if there is a syntax error.
Upon finding an error,
\fBvisudo\fR
will print a message stating the line number(s)
where the error occurred and the user will receive the
\(lqWhat now?\(rq
prompt.
At this point the user may enter
\(oqe\(cq
to re-edit the
\fIsudoers\fR
file,
\(oqx\(cq
to exit without saving the changes, or
\(oqQ\(cq
to quit and save changes.
The
\(oqQ\(cq
option should be used with extreme caution because if
\fBvisudo\fR
believes there to be a parse error, so will
\fBsudo\fR
and no one
will be able to run
\fBsudo\fR
again until the error is fixed.
If
\(oqe\(cq
is typed to edit the
\fIsudoers\fR
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
There are two
\fIsudoers\fR
settings that determine which editor
\fBvisudo\fR
will run.
.TP 10n
editor
A colon
(\(oq:\&\(cq)
separated list of editors allowed to be used with
\fBvisudo\fR.
\fBvisudo\fR
will choose the editor that matches the user's
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
environment variable if possible, or the first editor in the
list that exists and is executable.
Note that the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
and
\fREDITOR\fR
environment variables are not preserved by default when the
\fIenv_reset\fR
\fIsudoers\fR
option is enabled.
The default editor path is
\fI@editor@\fR
which can be set at compile time via the
\fR--with-editor\fR
configure option.
.TP 10n
env_editor
If set,
\fBvisudo\fR
will use the value of the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
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
\fIeditor\fR
variable.
\fBvisudo\fR
will then only use
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
if they match a value specified in
\fIeditor\fR.
If the
\fIenv_reset\fR
flag is enabled, the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
and/or
\fREDITOR\fR
environment variables must be present in the
\fIenv_keep\fR
list for the
\fIenv_editor\fR
flag to function when
\fBvisudo\fR
is invoked via
\fBsudo\fR.
The default value is
\fI@env_editor@\fR,
which can be set at compile time via the
\fR--with-env-editor\fR
configure option.
.PP
The options are as follows:
.TP 12n
\fB\-c\fR, \fB\--check\fR
Enable
\fIcheck-only\fR
mode.
The existing
\fIsudoers\fR
file (and any other files it includes) will be
checked for syntax errors.
If the path to the
\fIsudoers\fR
file was not specified,
\fBvisudo\fR
will also check the file owner and mode.
A message will be printed to the standard output describing the status of
\fIsudoers\fR
unless the
\fB\-q\fR
option was specified.
If the check completes successfully,
\fBvisudo\fR
will exit with a value of 0.
If an error is encountered,
\fBvisudo\fR
will exit with a value of 1.
.TP 12n
\fB\-f\fR \fIsudoers\fR, \fB\--file\fR=\fIsudoers\fR
Specify an alternate
\fIsudoers\fR
file location, see below.
As of version 1.8.27, the
\fIsudoers\fR
path can be specified without using the
\fB\-f\fR
option.
.TP 12n
\fB\-h\fR, \fB\--help\fR
Display a short help message to the standard output and exit.
.TP 12n
\fB\-q\fR, \fB\--quiet\fR
Enable
\fIquiet\fR
mode.
In this mode details about syntax errors are not printed.
This option is only useful when combined with
the
\fB\-c\fR
option.
.TP 12n
\fB\-s\fR, \fB\--strict\fR
Enable
\fIstrict\fR
checking of the
\fIsudoers\fR
file.
If an alias is referenced but not actually defined
or if there is a cycle in an alias,
\fBvisudo\fR
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
(\(oq_\(cq)
character.
.TP 12n
\fB\-V\fR, \fB\--version\fR
Print the
\fBvisudo\fR
and
\fIsudoers\fR
grammar versions and exit.
.PP
A
\fIsudoers\fR
file may be specified instead of the default,
\fI@sysconfdir@/sudoers\fR.
The lock file used is the specified
\fIsudoers\fR
file with
\(lq\.tmp\(rq
appended to it.
In
\fIcheck-only\fR
mode only,
\(oq-\(cq
may be used to indicate that
\fIsudoers\fR
will be read from the standard input.
Because the policy is evaluated in its entirety, it is not sufficient
to check an individual
\fIsudoers\fR
include file for syntax errors.
.SS "Debugging and sudoers plugin arguments"
\fBvisudo\fR
versions 1.8.4 and higher support a flexible debugging framework
that is configured via
\fRDebug\fR
lines in the
sudo.conf(@mansectform@)
file.
.PP
Starting with
\fBsudo\fR
1.8.12,
\fBvisudo\fR
will also parse the arguments to the
\fIsudoers\fR
plugin to override the default
\fIsudoers\fR
path name, UID, GID and file mode.
These arguments, if present, should be listed after the path to the plugin
(i.e., after
\fIsudoers.so\fR).
Multiple arguments may be specified, separated by white space.
For example:
.nf
.sp
.RS 6n
Plugin sudoers_policy sudoers.so sudoers_mode=0400
.RE
.fi
.PP
The following arguments are supported:
.TP 10n
sudoers_file=pathname
The
\fIsudoers_file\fR
argument can be used to override the default path to the
\fIsudoers\fR
file.
.TP 10n
sudoers_uid=uid
The
\fIsudoers_uid\fR
argument can be used to override the default owner of the sudoers file.
It should be specified as a numeric user ID.
.TP 10n
sudoers_gid=gid
The
\fIsudoers_gid\fR
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).
.TP 10n
sudoers_mode=mode
The
\fIsudoers_mode\fR
argument can be used to override the default file mode for the sudoers file.
It should be specified as an octal value.
.PP
For more information on configuring
sudo.conf(@mansectform@),
please refer to its manual.
.SH "ENVIRONMENT"
The following environment variables may be consulted depending on
the value of the
\fIeditor\fR
and
\fIenv_editor\fR
\fIsudoers\fR
settings:
.TP 17n
\fRSUDO_EDITOR\fR
Invoked by
\fBvisudo\fR
as the editor to use
.TP 17n
\fRVISUAL\fR
Used by
\fBvisudo\fR
if
\fRSUDO_EDITOR\fR
is not set
.TP 17n
\fREDITOR\fR
Used by
\fBvisudo\fR
if neither
\fRSUDO_EDITOR\fR
nor
\fRVISUAL\fR
is set
.SH "FILES"
.TP 26n
\fI@sysconfdir@/sudo.conf\fR
Sudo front end configuration
.TP 26n
\fI@sysconfdir@/sudoers\fR
List of who can run what
.TP 26n
\fI@sysconfdir@/sudoers.tmp\fR
Lock file for visudo
.SH "DIAGNOSTICS"
In addition to reporting
\fIsudoers\fR
parse errors,
\fBvisudo\fR
may produce the following messages:
.TP 6n
\fRsudoers file busy, try again later.\fR
Someone else is currently editing the
\fIsudoers\fR
file.
.TP 6n
\fR@sysconfdir@/sudoers.tmp: Permission denied\fR
You didn't run
\fBvisudo\fR
as root.
.TP 6n
\fRyou do not exist in the passwd database\fR
Your user ID does not appear in the system passwd database.
.TP 6n
\fRWarning: {User,Runas,Host,Cmnd}_Alias referenced but not defined\fR
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
(\(oq_\(cq)
character.
In the latter case, you can ignore the warnings
(\fBsudo\fR
will not complain)
\&.
The message is prefixed with the path name of the
\fIsudoers\fR
file and the line number where the undefined alias was used.
In
\fB\-s\fR
(strict) mode these are errors, not warnings.
.TP 6n
\fRWarning: unused {User,Runas,Host,Cmnd}_Alias\fR
The specified {User,Runas,Host,Cmnd}_Alias was defined but never
used.
The message is prefixed with the path name of the
\fIsudoers\fR
file and the line number where the unused alias was defined.
You may wish to comment out or remove the unused alias.
.TP 6n
\fRWarning: cycle in {User,Runas,Host,Cmnd}_Alias\fR
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
\fIsudoers\fR
file and the line number where the cycle was detected.
This is only a warning unless
\fBvisudo\fR
is run in
\fB\-s\fR
(strict) mode as
\fBsudo\fR
will ignore cycles when parsing
the
\fIsudoers\fR
file.
.TP 6n
\fRunknown defaults entry \&"name\&"\fR
The
\fIsudoers\fR
file contains a
\fRDefaults\fR
setting not recognized by
\fBvisudo\fR.
.SH "SEE ALSO"
vi(1),
sudo.conf(@mansectform@),
sudoers(@mansectform@),
sudo(@mansectsu@),
vipw(@mansectsu@)
.SH "AUTHORS"
Many people have worked on
\fBsudo\fR
over the years; this version consists of code written primarily by:
.sp
.RS 6n
Todd C. Miller
.RE
.PP
See the CONTRIBUTORS file in the
\fBsudo\fR
distribution (https://www.sudo.ws/contributors.html) for an
exhaustive list of people who have contributed to
\fBsudo\fR.
.SH "CAVEATS"
There is no easy way to prevent a user from gaining a root shell if
the editor used by
\fBvisudo\fR
allows shell escapes.
.SH "BUGS"
If you feel you have found a bug in
\fBvisudo\fR,
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"
\fBvisudo\fR
is provided
\(lqAS IS\(rq
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
\fBsudo\fR
or https://www.sudo.ws/license.html for complete details.