1VISUDO(8)                 BSD System Manager's Manual                VISUDO(8)
2

NAME

4     visudo — edit the sudoers file
5

SYNOPSIS

7     visudo [-chqsV] [[-f] sudoers]
8

DESCRIPTION

10     visudo edits the sudoers file in a safe fashion, analogous to vipw(8).
11     visudo locks the sudoers file against multiple simultaneous edits, pro‐
12     vides basic sanity checks, and checks for parse errors before installing
13     the edited file.  If the sudoers file is currently being edited you will
14     receive a message to try again later.
15
16     visudo parses the sudoers file after editing and will not save the
17     changes if there is a syntax error.  Upon finding an error, visudo will
18     print a message stating the line number(s) where the error occurred and
19     the user will receive the “What now?” prompt.  At this point the user may
20     enter ‘e’ to re-edit the sudoers file, ‘x’ to exit without saving the
21     changes, or ‘Q’ to quit and save changes.  The ‘Q’ option should be used
22     with extreme caution because if visudo believes there to be a parse
23     error, so will sudo and no one will be able to run sudo again until the
24     error is fixed.  If ‘e’ is typed to edit the sudoers file after a parse
25     error has been detected, the cursor will be placed on the line where the
26     error occurred (if the editor supports this feature).
27
28     There are two sudoers settings that determine which editor visudo will
29     run.
30
31     editor    A colon (‘:’) separated list of editors allowed to be used with
32               visudo.  visudo will choose the editor that matches the user's
33               SUDO_EDITOR, VISUAL or EDITOR environment variable if possible,
34               or the first editor in the list that exists and is executable.
35               Note that sudo does not preserve the SUDO_EDITOR, VISUAL or
36               EDITOR environment variables unless they are present in the
37               env_keep list or the env_reset option is disabled in the
38               sudoers file.  The default editor path is /bin/vi which can be
39               set at compile time via the --with-editor configure option.
40
41     env_editor
42               If set, visudo will use the value of the SUDO_EDITOR, VISUAL or
43               EDITOR environment variables before falling back on the default
44               editor list.  Note that visudo is typically run as root so this
45               option may allow a user with visudo privileges to run arbitrary
46               commands as root without logging.  An alternative is to place a
47               colon-separated list of “safe” editors int the editor variable.
48               visudo will then only use SUDO_EDITOR, VISUAL or EDITOR if they
49               match a value specified in editor.  If the env_reset flag is
50               enabled, the SUDO_EDITOR, VISUAL and/or EDITOR environment
51               variables must be present in the env_keep list for the
52               env_editor flag to function when visudo is invoked via sudo.
53               The default value is on, which can be set at compile time via
54               the --with-env-editor configure option.
55
56     The options are as follows:
57
58     -c, --check
59                 Enable check-only mode.  The existing sudoers file (and any
60                 other files it includes) will be checked for syntax errors.
61                 If the path to the sudoers file was not specified, visudo
62                 will also check the file owner and mode.  A message will be
63                 printed to the standard output describing the status of
64                 sudoers unless the -q option was specified.  If the check
65                 completes successfully, visudo will exit with a value of 0.
66                 If an error is encountered, visudo will exit with a value of
67                 1.
68
69     -f sudoers, --file=sudoers
70                 Specify an alternate sudoers file location, see below.  As of
71                 version 1.8.27, the sudoers path can be specified without
72                 using the -f option.
73
74     -h, --help  Display a short help message to the standard output and exit.
75
76     -q, --quiet
77                 Enable quiet mode.  In this mode details about syntax errors
78                 are not printed.  This option is only useful when combined
79                 with the -c option.
80
81     -s, --strict
82                 Enable strict checking of the sudoers file.  If an alias is
83                 referenced but not actually defined or if there is a cycle in
84                 an alias, visudo will consider this a parse error.  Note that
85                 it is not possible to differentiate between an alias and a
86                 host name or user name that consists solely of uppercase let‐
87                 ters, digits, and the underscore (‘_’) character.
88
89     -V, --version
90                 Print the visudo and sudoers grammar versions and exit.
91
92     A sudoers file may be specified instead of the default, /etc/sudoers.
93     The temporary file used is the specified sudoers file with “.tmp”
94     appended to it.  In check-only mode only, ‘-’ may be used to indicate
95     that sudoers will be read from the standard input.  Because the policy is
96     evaluated in its entirety, it is not sufficient to check an individual
97     sudoers include file for syntax errors.
98
99   Debugging and sudoers plugin arguments
100     visudo versions 1.8.4 and higher support a flexible debugging framework
101     that is configured via Debug lines in the sudo.conf(5) file.
102
103     Starting with sudo 1.8.12, visudo will also parse the arguments to the
104     sudoers plugin to override the default sudoers path name, UID, GID and
105     file mode.  These arguments, if present, should be listed after the path
106     to the plugin (i.e., after sudoers.so).  Multiple arguments may be speci‐
107     fied, separated by white space.  For example:
108
109           Plugin sudoers_policy sudoers.so sudoers_mode=0400
110
111     The following arguments are supported:
112
113     sudoers_file=pathname
114               The sudoers_file argument can be used to override the default
115               path to the sudoers file.
116
117     sudoers_uid=uid
118               The sudoers_uid argument can be used to override the default
119               owner of the sudoers file.  It should be specified as a numeric
120               user-ID.
121
122     sudoers_gid=gid
123               The sudoers_gid argument can be used to override the default
124               group of the sudoers file.  It must be specified as a numeric
125               group-ID (not a group name).
126
127     sudoers_mode=mode
128               The sudoers_mode argument can be used to override the default
129               file mode for the sudoers file.  It should be specified as an
130               octal value.
131
132     For more information on configuring sudo.conf(5), please refer to its
133     manual.
134

ENVIRONMENT

136     The following environment variables may be consulted depending on the
137     value of the editor and env_editor sudoers settings:
138
139     SUDO_EDITOR      Invoked by visudo as the editor to use
140
141     VISUAL           Used by visudo if SUDO_EDITOR is not set
142
143     EDITOR           Used by visudo if neither SUDO_EDITOR nor VISUAL is set
144

FILES

146     /etc/sudo.conf            Sudo front end configuration
147
148     /etc/sudoers              List of who can run what
149
150     /etc/sudoers.tmp          Default temporary file used by visudo
151

DIAGNOSTICS

153     In addition to reporting sudoers parse errors, visudo may produce the
154     following messages:
155
156     sudoers file busy, try again later.
157           Someone else is currently editing the sudoers file.
158
159     /etc/sudoers: Permission denied
160           You didn't run visudo as root.
161
162     you do not exist in the passwd database
163           Your user-ID does not appear in the system passwd database.
164
165     Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
166           Either you are trying to use an undeclared
167           {User,Runas,Host,Cmnd}_Alias or you have a user or host name listed
168           that consists solely of uppercase letters, digits, and the under‐
169           score (‘_’) character.  In the latter case, you can ignore the
170           warnings (sudo will not complain).  The message is prefixed with
171           the path name of the sudoers file and the line number where the
172           undefined alias was used.  In -s (strict) mode these are errors,
173           not warnings.
174
175     Warning: unused {User,Runas,Host,Cmnd}_Alias
176           The specified {User,Runas,Host,Cmnd}_Alias was defined but never
177           used.  The message is prefixed with the path name of the sudoers
178           file and the line number where the unused alias was defined.  You
179           may wish to comment out or remove the unused alias.
180
181     Warning: cycle in {User,Runas,Host,Cmnd}_Alias
182           The specified {User,Runas,Host,Cmnd}_Alias includes a reference to
183           itself, either directly or through an alias it includes.  The mes‐
184           sage is prefixed with the path name of the sudoers file and the
185           line number where the cycle was detected.  This is only a warning
186           unless visudo is run in -s (strict) mode as sudo will ignore cycles
187           when parsing the sudoers file.
188
189     unknown defaults entry "name"
190           The sudoers file contains a Defaults setting not recognized by
191           visudo.
192

SEE ALSO

194     vi(1), sudo.conf(5), sudoers(5), sudo(8), vipw(8)
195

AUTHORS

197     Many people have worked on sudo over the years; this version consists of
198     code written primarily by:
199
200           Todd C. Miller
201
202     See the CONTRIBUTORS file in the sudo distribution
203     (https://www.sudo.ws/contributors.html) for an exhaustive list of people
204     who have contributed to sudo.
205

CAVEATS

207     There is no easy way to prevent a user from gaining a root shell if the
208     editor used by visudo allows shell escapes.
209

BUGS

211     If you feel you have found a bug in visudo, please submit a bug report at
212     https://bugzilla.sudo.ws/
213

SUPPORT

215     Limited free support is available via the sudo-users mailing list, see
216     https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
217     the archives.
218

DISCLAIMER

220     visudo is provided “AS IS” and any express or implied warranties, includ‐
221     ing, but not limited to, the implied warranties of merchantability and
222     fitness for a particular purpose are disclaimed.  See the LICENSE file
223     distributed with sudo or https://www.sudo.ws/license.html for complete
224     details.
225
226Sudo 1.8.29                    October 20, 2019                    Sudo 1.8.29
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