1SUDO(8) MAINTENANCE COMMANDS SUDO(8)
2
6 sudo, sudoedit - execute a command as another user
7
9 sudo -h | -K | -k | -L | -V
10 sudo -v [-AknS] [-g group name|#gid] [-p prompt] [-u username|#uid]
12 sudo -l[l] [-AknS] [-g group name|#gid] [-p prompt] [-U user name]
14 [-u user name|#uid] [command]
15 sudo [-AbEHnPS] [-C fd] [-g group name|#gid] [-p prompt] [-r role]
17 [-t type] [-u user name|#uid] [VAR=value] [-i | -s] [command]
18 sudoedit [-AnS] [-C fd] [-g group name|#gid] [-p prompt]
20 [-u user name|#uid] file ...
21
23 sudo allows a permitted user to execute a command as the superuser or
24 another user, as specified in the sudoers file. The real and effective
25 uid and gid are set to match those of the target user as specified in
26 the passwd file and the group vector is initialized based on the group
27 file (unless the -P option was specified). If the invoking user is
28 root or if the target user is the same as the invoking user, no
29 password is required. Otherwise, sudo requires that users authenticate
30 themselves with a password by default (NOTE: in the default
31 configuration this is the user's password, not the root password).
32 Once a user has been authenticated, a time stamp is updated and the
33 user may then use sudo without a password for a short period of time (5
34 minutes unless overridden in sudoers).
35 When invoked as sudoedit, the -e option (described below), is implied.
37 sudo determines who is an authorized user by consulting the file
39 /etc/sudoers. By running sudo with the -v option, a user can update
40 the time stamp without running a command. If a password is required,
41 sudo will exit if the user's password is not entered within a
42 configurable time limit. The default password prompt timeout is 5
43 minutes.
44 If a user who is not listed in the sudoers file tries to run a command
46 via sudo, mail is sent to the proper authorities, as defined at
47 configure time or in the sudoers file (defaults to root). Note that
48 the mail will not be sent if an unauthorized user tries to run sudo
49 with the -l or -v option. This allows users to determine for
50 themselves whether or not they are allowed to use sudo.
51 If sudo is run by root and the SUDO_USER environment variable is set,
53 sudo will use this value to determine who the actual user is. This can
54 be used by a user to log commands through sudo even when a root shell
55 has been invoked. It also allows the -e option to remain useful even
56 when being run via a sudo-run script or program. Note however, that
57 the sudoers lookup is still done for root, not the user specified by
58 SUDO_USER.
59 sudo can log both successful and unsuccessful attempts (as well as
61 errors) to syslog(3), a log file, or both. By default sudo will log
62 via syslog(3) but this is changeable at configure time or via the
63 sudoers file.
64
66 sudo accepts the following command line options:
67 -A Normally, if sudo requires a password, it will read it from
69 the current terminal. If the -A (askpass) option is
70 specified, a (possibly graphical) helper program is
71 executed to read the user's password and output the
72 password to the standard output. If the SUDO_ASKPASS
73 environment variable is set, it specifies the path to the
74 helper program. Otherwise, the value specified by the
75 askpass option in sudoers(5) is used.
76 -b The -b (background) option tells sudo to run the given
78 command in the background. Note that if you use the -b
79 option you cannot use shell job control to manipulate the
80 process.
81 -C fd Normally, sudo will close all open file descriptors other
83 than standard input, standard output and standard error.
84 The -C (close from) option allows the user to specify a
85 starting point above the standard error (file descriptor
86 three). Values less than three are not permitted. This
87 option is only available if the administrator has enabled
88 the closefrom_override option in sudoers(5).
89 -E The -E (preserve environment) option will override the
91 env_reset option in sudoers(5)). It is only available when
92 either the matching command has the SETENV tag or the
93 setenv option is set in sudoers(5).
94 -e The -e (edit) option indicates that, instead of running a
96 command, the user wishes to edit one or more files. In
97 lieu of a command, the string "sudoedit" is used when
98 consulting the sudoers file. If the user is authorized by
99 sudoers the following steps are taken:
100 1. Temporary copies are made of the files to be edited
102 with the owner set to the invoking user.
103 2. The editor specified by the SUDO_EDITOR, VISUAL or
105 EDITOR environment variables is run to edit the
106 temporary files. If none of SUDO_EDITOR, VISUAL or
107 EDITOR are set, the first program listed in the editor
108 sudoers variable is used.
109 3. If they have been modified, the temporary files are
111 copied back to their original location and the
112 temporary versions are removed.
113 If the specified file does not exist, it will be created.
115 Note that unlike most commands run by sudo, the editor is
116 run with the invoking user's environment unmodified. If,
117 for some reason, sudo is unable to update a file with its
118 edited version, the user will receive a warning and the
119 edited copy will remain in a temporary file.
120 -g group Normally, sudo sets the primary group to the one specified
122 by the passwd database for the user the command is being
123 run as (by default, root). The -g (group) option causes
124 sudo to run the specified command with the primary group
125 set to group. To specify a gid instead of a group name,
126 use #gid. When running commands as a gid, many shells
127 require that the '#' be escaped with a backslash ('\'). If
128 no -u option is specified, the command will be run as the
129 invoking user (not root). In either case, the primary
130 group will be set to group.
131 -H The -H (HOME) option sets the HOME environment variable to
133 the homedir of the target user (root by default) as
134 specified in passwd(5). The default handling of the HOME
135 environment variable depends on sudoers(5) settings. By
136 default, sudo will set HOME if env_reset or always_set_home
137 are set, or if set_home is set and the -s option is
138 specified on the command line.
139 -h The -h (help) option causes sudo to print a usage message
141 and exit.
142 -i [command]
144 The -i (simulate initial login) option runs the shell
145 specified in the passwd(5) entry of the target user as a
146 login shell. This means that login-specific resource files
147 such as .profile or .login will be read by the shell. If a
148 command is specified, it is passed to the shell for
149 execution. Otherwise, an interactive shell is executed.
150 sudo attempts to change to that user's home directory
151 before running the shell. It also initializes the
152 environment, leaving DISPLAY and TERM unchanged, setting
153 HOME, MAIL, SHELL, USER, LOGNAME, and PATH, as well as the
154 contents of /etc/environment on Linux and AIX systems. All
155 other environment variables are removed.
156 -K The -K (sure kill) option is like -k except that it removes
158 the user's time stamp entirely and may not be used in
159 conjunction with a command or other option. This option
160 does not require a password.
161 -k When used by itself, the -k (kill) option to sudo
163 invalidates the user's time stamp by setting the time on it
164 to the Epoch. The next time sudo is run a password will be
165 required. This option does not require a password and was
166 added to allow a user to revoke sudo permissions from a
167 .logout file.
168 When used in conjunction with a command or an option that
170 may require a password, the -k option will cause sudo to
171 ignore the user's time stamp file. As a result, sudo will
172 prompt for a password (if one is required by sudoers) and
173 will not update the user's time stamp file.
174 -L The -L (list defaults) option will list the parameters that
176 may be set in a Defaults line along with a short
177 description for each. This option will be removed from a
178 future version of sudo.
179 -l[l] [command]
181 If no command is specified, the -l (list) option will list
182 the allowed (and forbidden) commands for the invoking user
183 (or the user specified by the -U option) on the current
184 host. If a command is specified and is permitted by
185 sudoers, the fully-qualified path to the command is
186 displayed along with any command line arguments. If
187 command is specified but not allowed, sudo will exit with a
188 status value of 1. If the -l option is specified with an l
189 argument (i.e. -ll), or if -l is specified multiple times,
190 a longer list format is used.
191 -n The -n (non-interactive) option prevents sudo from
193 prompting the user for a password. If a password is
194 required for the command to run, sudo will display an error
195 messages and exit.
196 -P The -P (preserve group vector) option causes sudo to
198 preserve the invoking user's group vector unaltered. By
199 default, sudo will initialize the group vector to the list
200 of groups the target user is in. The real and effective
201 group IDs, however, are still set to match the target user.
202 -p prompt The -p (prompt) option allows you to override the default
204 password prompt and use a custom one. The following
205 percent (`%') escapes are supported:
206 %H expanded to the local host name including the domain
208 name (on if the machine's host name is fully qualified
209 or the fqdn sudoers option is set)
210 %h expanded to the local host name without the domain name
212 %p expanded to the user whose password is being asked for
214 (respects the rootpw, targetpw and runaspw flags in
215 sudoers)
216 %U expanded to the login name of the user the command will
218 be run as (defaults to root)
219 %u expanded to the invoking user's login name
221 %% two consecutive % characters are collapsed into a
223 single % character
224 The prompt specified by the -p option will override the
226 system password prompt on systems that support PAM unless
227 the passprompt_override flag is disabled in sudoers.
228 -r role The -r (role) option causes the new (SELinux) security
230 context to have the role specified by role.
231 -S The -S (stdin) option causes sudo to read the password from
233 the standard input instead of the terminal device. The
234 password must be followed by a newline character.
235 -s [command]
237 The -s (shell) option runs the shell specified by the SHELL
238 environment variable if it is set or the shell as specified
239 in passwd(5). If a command is specified, it is passed to
240 the shell for execution. Otherwise, an interactive shell
241 is executed.
242 -t type The -t (type) option causes the new (SELinux) security
244 context to have the type specified by type. If no type is
245 specified, the default type is derived from the specified
246 role.
247 -U user The -U (other user) option is used in conjunction with the
249 -l option to specify the user whose privileges should be
250 listed. Only root or a user with sudo ALL on the current
251 host may use this option.
252 -u user The -u (user) option causes sudo to run the specified
254 command as a user other than root. To specify a uid
255 instead of a user name, use #uid. When running commands as
256 a uid, many shells require that the '#' be escaped with a
257 backslash ('\'). Note that if the targetpw Defaults option
258 is set (see sudoers(5)) it is not possible to run commands
259 with a uid not listed in the password database.
260 -V The -V (version) option causes sudo to print the version
262 number and exit. If the invoking user is already root the
263 -V option will print out a list of the defaults sudo was
264 compiled with as well as the machine's local network
265 addresses.
266 -v If given the -v (validate) option, sudo will update the
268 user's time stamp, prompting for the user's password if
269 necessary. This extends the sudo timeout for another 5
270 minutes (or whatever the timeout is set to in sudoers) but
271 does not run a command.
272 -- The -- option indicates that sudo should stop processing
274 command line arguments.
275 Environment variables to be set for the command may also be passed on
277 the command line in the form of VAR=value, e.g.
278 LD_LIBRARY_PATH=/usr/local/pkg/lib. Variables passed on the command
279 line are subject to the same restrictions as normal environment
280 variables with one important exception. If the setenv option is set in
281 sudoers, the command to be run has the SETENV tag set or the command
282 matched is ALL, the user may set variables that would overwise be
283 forbidden. See sudoers(5) for more information.
284
286 Upon successful execution of a program, the exit status from sudo will
287 simply be the exit status of the program that was executed.
288 Otherwise, sudo quits with an exit value of 1 if there is a
290 configuration/permission problem or if sudo cannot execute the given
291 command. In the latter case the error string is printed to stderr. If
292 sudo cannot stat(2) one or more entries in the user's PATH an error is
293 printed on stderr. (If the directory does not exist or if it is not
294 really a directory, the entry is ignored and no error is printed.)
295 This should not happen under normal circumstances. The most common
296 reason for stat(2) to return "permission denied" is if you are running
297 an automounter and one of the directories in your PATH is on a machine
298 that is currently unreachable.
299
301 sudo tries to be safe when executing external commands.
302 There are two distinct ways to deal with environment variables. By
304 default, the env_reset sudoers option is enabled. This causes commands
305 to be executed with a minimal environment containing TERM, PATH, HOME,
306 SHELL, LOGNAME, USER and USERNAME in addition to variables from the
307 invoking process permitted by the env_check and env_keep sudoers
308 options. There is effectively a whitelist for environment variables.
309 If, however, the env_reset option is disabled in sudoers, any variables
311 not explicitly denied by the env_check and env_delete options are
312 inherited from the invoking process. In this case, env_check and
313 env_delete behave like a blacklist. Since it is not possible to
314 blacklist all potentially dangerous environment variables, use of the
315 default env_reset behavior is encouraged.
316 In all cases, environment variables with a value beginning with () are
318 removed as they could be interpreted as bash functions. The list of
319 environment variables that sudo allows or denies is contained in the
320 output of sudo -V when run as root.
321 Note that the dynamic linker on most operating systems will remove
323 variables that can control dynamic linking from the environment of
324 setuid executables, including sudo. Depending on the operating system
325 this may include _RLD*, DYLD_*, LD_*, LDR_*, LIBPATH, SHLIB_PATH, and
326 others. These type of variables are removed from the environment
327 before sudo even begins execution and, as such, it is not possible for
328 sudo to preserve them.
329 To prevent command spoofing, sudo checks "." and "" (both denoting
331 current directory) last when searching for a command in the user's PATH
332 (if one or both are in the PATH). Note, however, that the actual PATH
333 environment variable is not modified and is passed unchanged to the
334 program that sudo executes.
335 sudo will check the ownership of its time stamp directory (/var/db/sudo
337 by default) and ignore the directory's contents if it is not owned by
338 root or if it is writable by a user other than root. On systems that
339 allow non-root users to give away files via chown(2), if the time stamp
340 directory is located in a directory writable by anyone (e.g., /tmp), it
341 is possible for a user to create the time stamp directory before sudo
342 is run. However, because sudo checks the ownership and mode of the
343 directory and its contents, the only damage that can be done is to
344 "hide" files by putting them in the time stamp dir. This is unlikely
345 to happen since once the time stamp dir is owned by root and
346 inaccessible by any other user, the user placing files there would be
347 unable to get them back out. To get around this issue you can use a
348 directory that is not world-writable for the time stamps (/var/adm/sudo
349 for instance) or create /var/db/sudo with the appropriate owner (root)
350 and permissions (0700) in the system startup files.
351 sudo will not honor time stamps set far in the future. Timestamps with
353 a date greater than current_time + 2 * TIMEOUT will be ignored and sudo
354 will log and complain. This is done to keep a user from creating
355 his/her own time stamp with a bogus date on systems that allow users to
356 give away files.
357 On systems where the boot time is available, sudo will also not honor
359 time stamps from before the machine booted.
360 Since time stamp files live in the file system, they can outlive a
362 user's login session. As a result, a user may be able to login, run a
363 command with sudo after authenticating, logout, login again, and run
364 sudo without authenticating so long as the time stamp file's
365 modification time is within 5 minutes (or whatever the timeout is set
366 to in sudoers). When the tty_tickets option is enabled in sudoers, the
367 time stamp has per-tty granularity but still may outlive the user's
368 session. On Linux systems where the devpts filesystem is used, Solaris
369 systems with the devices filesystem, as well as other systems that
370 utilize a devfs filesystem that monotonically increase the inode number
371 of devices as they are created (such as Mac OS X), sudo is able to
372 determine when a tty-based time stamp file is stale and will ignore it.
373 Administrators should not rely on this feature as it is not universally
374 available.
375 Please note that sudo will normally only log the command it explicitly
377 runs. If a user runs a command such as sudo su or sudo sh, subsequent
378 commands run from that shell will not be logged, nor will sudo's access
379 control affect them. The same is true for commands that offer shell
380 escapes (including most editors). Because of this, care must be taken
381 when giving users access to commands via sudo to verify that the
382 command does not inadvertently give the user an effective root shell.
383 For more information, please see the PREVENTING SHELL ESCAPES section
384 in sudoers(5).
385
387 sudo utilizes the following environment variables:
388 EDITOR Default editor to use in -e (sudoedit) mode if neither
390 SUDO_EDITOR nor VISUAL is set
391 MAIL In -i mode or when env_reset is enabled in sudoers, set
393 to the mail spool of the target user
394 HOME Set to the home directory of the target user if -i or
396 -H are specified, env_reset or always_set_home are set
397 in sudoers, or when the -s option is specified and
398 set_home is set in sudoers
399 PATH Set to a sane value if the secure_path sudoers option
401 is set.
402 SHELL Used to determine shell to run with -s option
404 SUDO_ASKPASS Specifies the path to a helper program used to read the
406 password if no terminal is available or if the -A
407 option is specified.
408 SUDO_COMMAND Set to the command run by sudo
410 SUDO_EDITOR Default editor to use in -e (sudoedit) mode
412 SUDO_GID Set to the group ID of the user who invoked sudo
414 SUDO_PROMPT Used as the default password prompt
416 SUDO_PS1 If set, PS1 will be set to its value for the program
418 being run
419 SUDO_UID Set to the user ID of the user who invoked sudo
421 SUDO_USER Set to the login of the user who invoked sudo
423 USER Set to the target user (root unless the -u option is
425 specified)
426 VISUAL Default editor to use in -e (sudoedit) mode if
428 SUDO_EDITOR is not set
429
431 /etc/sudoers List of who can run what
432 /var/db/sudo Directory containing time stamps
434 /etc/environment Initial environment for -i mode on Linux and
436 AIX
437
439 Note: the following examples assume suitable sudoers(5) entries.
440 To get a file listing of an unreadable directory:
442 $ sudo ls /usr/local/protected
444 To list the home directory of user yaz on a machine where the file
446 system holding ~yaz is not exported as root:
447 $ sudo -u yaz ls ~yaz
449 To edit the index.html file as user www:
451 $ sudo -u www vi ~www/htdocs/index.html
453 To view system logs only accessible to root and users in the adm group:
455 $ sudo -g adm view /var/log/syslog
457 To run an editor as jim with a different primary group:
459 $ sudo -u jim -g audio vi ~jim/sound.txt
461 To shutdown a machine:
463 $ sudo shutdown -r +15 "quick reboot"
465 To make a usage listing of the directories in the /home partition.
467 Note that this runs the commands in a sub-shell to make the cd and file
468 redirection work.
469 $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE"
471
473 grep(1), su(1), stat(2), passwd(5), sudoers(5), visudo(8)
474
476 Many people have worked on sudo over the years; this version consists
477 of code written primarily by:
478 Todd C. Miller
480 See the HISTORY file in the sudo distribution or visit
482 http://www.sudo.ws/sudo/history.html for a short history of sudo.
483
485 There is no easy way to prevent a user from gaining a root shell if
486 that user is allowed to run arbitrary commands via sudo. Also, many
487 programs (such as editors) allow the user to run commands via shell
488 escapes, thus avoiding sudo's checks. However, on most systems it is
489 possible to prevent shell escapes with sudo's noexec functionality.
490 See the sudoers(5) manual for details.
491 It is not meaningful to run the cd command directly via sudo, e.g.,
493 $ sudo cd /usr/local/protected
495 since when the command exits the parent process (your shell) will still
497 be the same. Please see the EXAMPLES section for more information.
498 If users have sudo ALL there is nothing to prevent them from creating
500 their own program that gives them a root shell regardless of any '!'
501 elements in the user specification.
502 Running shell scripts via sudo can expose the same kernel bugs that
504 make setuid shell scripts unsafe on some operating systems (if your OS
505 has a /dev/fd/ directory, setuid shell scripts are generally safe).
506
508 If you feel you have found a bug in sudo, please submit a bug report at
509 http://www.sudo.ws/sudo/bugs/
510
512 Limited free support is available via the sudo-users mailing list, see
513 http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
514 the archives.
515
517 sudo is provided ``AS IS'' and any express or implied warranties,
518 including, but not limited to, the implied warranties of
519 merchantability and fitness for a particular purpose are disclaimed.
520 See the LICENSE file distributed with sudo or
521 http://www.sudo.ws/sudo/license.html for complete details.
5221.7.4 July 19, 2010 SUDO(8)