Annotation of embedaddon/sudo/doc/sudo.pod, revision 1.1.1.1
1.1 misho 1: Copyright (c) 1994-1996, 1998-2005, 2007-2011
2: Todd C. Miller <Todd.Miller@courtesan.com>
3:
4: Permission to use, copy, modify, and distribute this software for any
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7:
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14: OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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16:
17: Sponsored in part by the Defense Advanced Research Projects
18: Agency (DARPA) and Air Force Research Laboratory, Air Force
19: Materiel Command, USAF, under agreement number F39502-99-1-0512.
20:
21: =pod
22:
23: =head1 NAME
24:
25: sudo, sudoedit - execute a command as another user
26:
27: =head1 SYNOPSIS
28:
29: B<sudo> S<[B<-D> I<level>]> B<-h> | B<-K> | B<-k> | B<-V>
30:
31: B<sudo> B<-v> [B<-AknS>]
32: S<[B<-a> I<auth_type>]>
33: S<[B<-D> I<level>]>
34: S<[B<-g> I<group name>|I<#gid>]> S<[B<-p> I<prompt>]>
35: S<[B<-u> I<user name>|I<#uid>]>
36:
37: B<sudo> B<-l[l]> [B<-AknS>]
38: S<[B<-a> I<auth_type>]>
39: S<[B<-D> I<level>]>
40: S<[B<-g> I<group name>|I<#gid>]> S<[B<-p> I<prompt>]>
41: S<[B<-U> I<user name>]> S<[B<-u> I<user name>|I<#uid>]> [I<command>]
42:
43: B<sudo> [B<-AbEHnPS>]
44: S<[B<-a> I<auth_type>]>
45: S<[B<-C> I<fd>]>
46: S<[B<-D> I<level>]>
47: S<[B<-c> I<class>|I<->]>
48: S<[B<-g> I<group name>|I<#gid>]> S<[B<-p> I<prompt>]>
49: S<[B<-r> I<role>]> S<[B<-t> I<type>]>
50: S<[B<-u> I<user name>|I<#uid>]>
51: S<[B<VAR>=I<value>]> S<[B<-i> | B<-s>]> [I<command>]
52:
53: B<sudoedit> [B<-AnS>]
54: S<[B<-a> I<auth_type>]>
55: S<[B<-C> I<fd>]>
56: S<[B<-c> I<class>|I<->]>
57: S<[B<-D> I<level>]>
58: S<[B<-g> I<group name>|I<#gid>]> S<[B<-p> I<prompt>]>
59: S<[B<-u> I<user name>|I<#uid>]> file ...
60:
61: =head1 DESCRIPTION
62:
63: B<sudo> allows a permitted user to execute a I<command> as the
64: superuser or another user, as specified by the security policy.
65: The real and effective uid and gid are set to match those of the
66: target user, as specified in the password database, and the group
67: vector is initialized based on the group database (unless the B<-P>
68: option was specified).
69:
70: B<sudo> supports a plugin architecture for security policies and
71: input/output logging. Third parties can develop and distribute
72: their own policy and I/O logging modules to work seemlessly with
73: the B<sudo> front end. The default security policy is I<sudoers>,
74: which is configured via the file F<@sysconfdir@/sudoers>, or via
75: LDAP. See the L<PLUGINS> section for more information.
76:
77: The security policy determines what privileges, if any, a user has
78: to run B<sudo>. The policy may require that users authenticate
79: themselves with a password or another authentication mechanism. If
80: authentication is required, B<sudo> will exit if the user's password
81: is not entered within a configurable time limit. This limit is
82: policy-specific; the default password prompt timeout for the
83: I<sudoers> security policy is C<@password_timeout@> minutes.
84:
85: Security policies may support credential caching to allow the user
86: to run B<sudo> again for a period of time without requiring
87: authentication. The I<sudoers> policy caches credentials for
88: C<@timeout@> minutes, unless overridden in L<sudoers(5)>. By
89: running B<sudo> with the B<-v> option, a user can update the cached
90: credentials without running a I<command>.
91:
92: When invoked as B<sudoedit>, the B<-e> option (described below),
93: is implied.
94:
95: Security policies may log successful and failed attempts to use
96: B<sudo>. If an I/O plugin is configured, the running command's
97: input and output may be logged as well.
98:
99: =head1 OPTIONS
100:
101: B<sudo> accepts the following command line options:
102:
103: =over 12
104:
105: =item -A
106:
107: Normally, if B<sudo> requires a password, it will read it from the
108: user's terminal. If the B<-A> (I<askpass>) option is specified,
109: a (possibly graphical) helper program is executed to read the user's
110: password and output the password to the standard output. If the
111: C<SUDO_ASKPASS> environment variable is set, it specifies the path
112: to the helper program. Otherwise, if F<@sysconfdir@/sudo.conf>
113: contains a line specifying the askpass program, that value will be
114: used. For example:
115:
116: # Path to askpass helper program
117: Path askpass /usr/X11R6/bin/ssh-askpass
118:
119: If no askpass program is available, sudo will exit with an error.
120:
121: =item -a I<type>
122:
123: The B<-a> (I<authentication type>) option causes B<sudo> to use the
124: specified authentication type when validating the user, as allowed
125: by F</etc/login.conf>. The system administrator may specify a list
126: of sudo-specific authentication methods by adding an "auth-sudo"
127: entry in F</etc/login.conf>. This option is only available on systems
128: that support BSD authentication.
129:
130: =item -b
131:
132: The B<-b> (I<background>) option tells B<sudo> to run the given
133: command in the background. Note that if you use the B<-b>
134: option you cannot use shell job control to manipulate the process.
135: Most interactive commands will fail to work properly in background
136: mode.
137:
138: =item -C I<fd>
139:
140: Normally, B<sudo> will close all open file descriptors other than
141: standard input, standard output and standard error. The B<-C>
142: (I<close from>) option allows the user to specify a starting point
143: above the standard error (file descriptor three). Values less than
144: three are not permitted. The security policy may restrict the
145: user's ability to use the B<-C> option. The I<sudoers> policy only
146: permits use of the B<-C> option when the administrator has enabled
147: the I<closefrom_override> option.
148:
149: =item -c I<class>
150:
151: The B<-c> (I<class>) option causes B<sudo> to run the specified command
152: with resources limited by the specified login class. The I<class>
153: argument can be either a class name as defined in F</etc/login.conf>,
154: or a single '-' character. Specifying a I<class> of C<-> indicates
155: that the command should be run restricted by the default login
156: capabilities for the user the command is run as. If the I<class>
157: argument specifies an existing user class, the command must be run
158: as root, or the B<sudo> command must be run from a shell that is already
159: root. This option is only available on systems with BSD login classes.
160:
161: =item -D I<level>
162:
163: Enable debugging of B<sudo> plugins and B<sudo> itself. The I<level>
164: may be a value from 1 through 9.
165:
166: =item -E
167:
168: The B<-E> (I<preserve> I<environment>) option indicates to the
169: security policy that the user wishes to preserve their existing
170: environment variables. The security policy may return an error if
171: the B<-E> option is specified and the user does not have permission
172: to preserve the environment.
173:
174: =item -e
175:
176: The B<-e> (I<edit>) option indicates that, instead of running a
177: command, the user wishes to edit one or more files. In lieu of a
178: command, the string "sudoedit" is used when consulting the security
179: policy. If the user is authorized by the policy, the following
180: steps are taken:
181:
182: =over 4
183:
184: =item 1.
185:
186: Temporary copies are made of the files to be edited with the owner
187: set to the invoking user.
188:
189: =item 2.
190:
191: The editor specified by the policy is run to edit the temporary files.
192: The I<sudoers> policy uses the C<SUDO_EDITOR>, C<VISUAL> and C<EDITOR>
193: environment variables (in that order). If none of C<SUDO_EDITOR>,
194: C<VISUAL> or C<EDITOR> are set, the first program listed in the
195: I<editor> L<sudoers(5)> option is used.
196:
197: =item 3.
198:
199: If they have been modified, the temporary files are copied back to
200: their original location and the temporary versions are removed.
201:
202: =back
203:
204: If the specified file does not exist, it will be created. Note
205: that unlike most commands run by B<sudo>, the editor is run with
206: the invoking user's environment unmodified. If, for some reason,
207: B<sudo> is unable to update a file with its edited version, the
208: user will receive a warning and the edited copy will remain in a
209: temporary file.
210:
211: =item -g I<group>
212:
213: Normally, B<sudo> runs a command with the primary group set to the
214: one specified by the password database for the user the command is
215: being run as (by default, root). The B<-g> (I<group>) option causes
216: B<sudo> to run the command with the primary group set to I<group>
217: instead. To specify a I<gid> instead of a I<group name>, use
218: I<#gid>. When running commands as a I<gid>, many shells require
219: that the '#' be escaped with a backslash ('\'). If no B<-u> option
220: is specified, the command will be run as the invoking user (not
221: root). In either case, the primary group will be set to I<group>.
222:
223: =item -H
224:
225: The B<-H> (I<HOME>) option requests that the security policy set
226: the C<HOME> environment variable to the home directory of the target
227: user (root by default) as specified by the password database.
228: Depending on the policy, this may be the default behavior.
229:
230: =item -h
231:
232: The B<-h> (I<help>) option causes B<sudo> to print a short help message
233: to the standard output and exit.
234:
235: =item -i [command]
236:
237: The B<-i> (I<simulate initial login>) option runs the shell specified
238: by the password database entry of the target user as a login shell.
239: This means that login-specific resource files such as C<.profile>
240: or C<.login> will be read by the shell. If a command is specified,
241: it is passed to the shell for execution via the shell's B<-c> option.
242: If no command is specified, an interactive shell is executed.
243: B<sudo> attempts to change to that user's home directory before
244: running the shell. The security policy shall initialize the
245: environment to a minimal set of variables, similar to what is present
246: when a user logs in. The I<Command Environment> section in the
247: L<sudoers(5)> manual documents how the B<-i> option affects the
248: environment in which a command is run when the I<sudoers> policy
249: is in use.
250:
251: =item -K
252:
253: The B<-K> (sure I<kill>) option is like B<-k> except that it removes
254: the user's cached credentials entirely and may not be used in
255: conjunction with a command or other option. This option does not
256: require a password. Not all security policies support credential
257: caching.
258:
259: =item -k [command]
260:
261: When used alone, the B<-k> (I<kill>) option to B<sudo> invalidates
262: the user's cached credentials. The next time B<sudo> is run a
263: password will be required. This option does not require a password
264: and was added to allow a user to revoke B<sudo> permissions from a
265: .logout file. Not all security policies support credential
266: caching.
267:
268: When used in conjunction with a command or an option that may require
269: a password, the B<-k> option will cause B<sudo> to ignore the user's
270: cached credentials. As a result, B<sudo> will prompt for a password
271: (if one is required by the security policy) and will not update the
272: user's cached credentials.
273:
274: =item -l[l] [I<command>]
275:
276: If no I<command> is specified, the B<-l> (I<list>) option will list
277: the allowed (and forbidden) commands for the invoking user (or the
278: user specified by the B<-U> option) on the current host. If a
279: I<command> is specified and is permitted by the security policy,
280: the fully-qualified path to the command is displayed along with any
281: command line arguments. If I<command> is specified but not allowed,
282: B<sudo> will exit with a status value of 1. If the B<-l> option
283: is specified with an B<l> argument (i.e. B<-ll>), or if B<-l> is
284: specified multiple times, a longer list format is used.
285:
286: =item -n
287:
288: The B<-n> (I<non-interactive>) option prevents B<sudo> from prompting
289: the user for a password. If a password is required for the command
290: to run, B<sudo> will display an error messages and exit.
291:
292: =item -P
293:
294: The B<-P> (I<preserve> I<group vector>) option causes B<sudo> to
295: preserve the invoking user's group vector unaltered. By default,
296: the I<sudoers> policy will initialize the group vector to the list
297: of groups the target user is in. The real and effective group IDs,
298: however, are still set to match the target user.
299:
300: =item -p I<prompt>
301:
302: The B<-p> (I<prompt>) option allows you to override the default
303: password prompt and use a custom one. The following percent (`C<%>')
304: escapes are supported by the I<sudoers> policy:
305:
306: =over 4
307:
308: =item C<%H>
309:
310: expanded to the host name including the domain name (on if
311: the machine's host name is fully qualified or the I<fqdn> option
312: is set in L<sudoers(5)>)
313:
314: =item C<%h>
315:
316: expanded to the local host name without the domain name
317:
318: =item C<%p>
319:
320: expanded to the name of the user whose password is being requested
321: (respects the I<rootpw>, I<targetpw> and I<runaspw> flags in
322: L<sudoers(5)>)
323:
324: =item C<%U>
325:
326: expanded to the login name of the user the command will be run as
327: (defaults to root unless the C<-u> option is also specified)
328:
329: =item C<%u>
330:
331: expanded to the invoking user's login name
332:
333: =item C<%%>
334:
335: two consecutive C<%> characters are collapsed into a single C<%> character
336:
337: =back
338:
339: The prompt specified by the B<-p> option will override the system
340: password prompt on systems that support PAM unless the
341: I<passprompt_override> flag is disabled in I<sudoers>.
342:
343: =item -r I<role>
344:
345: The B<-r> (I<role>) option causes the new (SELinux) security context to
346: have the role specified by I<role>.
347:
348: =item -S
349:
350: The B<-S> (I<stdin>) option causes B<sudo> to read the password from
351: the standard input instead of the terminal device. The password must
352: be followed by a newline character.
353:
354: =item -s [command]
355:
356: The B<-s> (I<shell>) option runs the shell specified by the I<SHELL>
357: environment variable if it is set or the shell as specified in the
358: password database. If a command is specified, it is passed to the
359: shell for execution via the shell's B<-c> option. If no command
360: is specified, an interactive shell is executed.
361:
362: =item -t I<type>
363:
364: The B<-t> (I<type>) option causes the new (SELinux) security context to
365: have the type specified by I<type>. If no type is specified, the default
366: type is derived from the specified role.
367:
368: =item -U I<user>
369:
370: The B<-U> (I<other user>) option is used in conjunction with the
371: B<-l> option to specify the user whose privileges should be listed.
372: The security policy may restrict listing other users' privileges.
373: The I<sudoers> policy only allows root or a user with the C<ALL>
374: privilege on the current host to use this option.
375:
376: =item -u I<user>
377:
378: The B<-u> (I<user>) option causes B<sudo> to run the specified
379: command as a user other than I<root>. To specify a I<uid> instead
380: of a I<user name>, use I<#uid>. When running commands as a I<uid>,
381: many shells require that the '#' be escaped with a backslash ('\').
382: Security policies may restrict I<uid>s to those listed in the
383: password database. The I<sudoers> policy allows I<uid>s that are
384: not in the password database as long as the I<targetpw> option is
385: not set. Other security policies may not support this.
386:
387: =item -V
388:
389: The B<-V> (I<version>) option causes B<sudo> to print its version
390: string and the version string of the security policy plugin and any
391: I/O plugins. If the invoking user is already root the B<-V> option
392: will display the arguments passed to configure when I<sudo> was
393: built and plugins may display more verbose information such as
394: default options.
395:
396: =item -v
397:
398: When given the B<-v> (I<validate>) option, B<sudo> will update the
399: user's cached credentials, authenticating the user's password if
400: necessary. For the I<sudoers> plugin, this extends the B<sudo>
401: timeout for another C<@timeout@> minutes (or whatever the timeout
402: is set to in I<sudoers>) but does not run a command. Not all
403: security policies support cached credentials.
404:
405: =item --
406:
407: The B<--> option indicates that B<sudo> should stop processing command
408: line arguments.
409:
410: =back
411:
412: Environment variables to be set for the command may also be passed
413: on the command line in the form of B<VAR>=I<value>, e.g.
414: B<LD_LIBRARY_PATH>=I</usr/local/pkg/lib>. Variables passed on the
415: command line are subject to the same restrictions as normal environment
416: variables with one important exception. If the I<setenv> option
417: is set in I<sudoers>, the command to be run has the C<SETENV> tag
418: set or the command matched is C<ALL>, the user may set variables
419: that would overwise be forbidden. See L<sudoers(5)> for more information.
420:
421: =head1 PLUGINS
422:
423: Plugins are dynamically loaded based on the contents of the
424: F<@sysconfdir@/sudo.conf> file. If no F<@sysconfdir@/sudo.conf>
425: file is present, or it contains no C<Plugin> lines, B<sudo>
426: will use the traditional I<sudoers> security policy and I/O logging,
427: which corresponds to the following F<@sysconfdir@/sudo.conf> file.
428:
429: #
430: # Default @sysconfdir@/sudo.conf file
431: #
432: # Format:
433: # Plugin plugin_name plugin_path
434: # Path askpass /path/to/askpass
435: # Path noexec /path/to/noexec.so
436: #
437: # The plugin_path is relative to @prefix@/libexec unless
438: # fully qualified.
439: # The plugin_name corresponds to a global symbol in the plugin
440: # that contains the plugin interface structure.
441: #
442: Plugin policy_plugin sudoers.so
443: Plugin io_plugin sudoers.so
444:
445: A C<Plugin> line consists of the C<Plugin> keyword, followed by the
446: I<symbol_name> and the I<path> to the shared object containing the
447: plugin. The I<symbol_name> is the name of the C<struct policy_plugin>
448: or C<struct io_plugin> in the plugin shared object. The I<path>
449: may be fully qualified or relative. If not fully qualified it is
450: relative to the F<@prefix@/libexec> directory. Any additional
451: parameters after the I<path> are ignored. Lines that don't begin
452: with C<Plugin> or C<Path> are silently ignored
453:
454: For more information, see the L<sudo_plugin(8)> manual.
455:
456: =head1 PATHS
457:
458: A C<Path> line consists of the C<Path> keyword, followed by the
459: name of the path to set and its value. E.g.
460:
461: Path noexec @noexec_file@
462: Path askpass /usr/X11R6/bin/ssh-askpass
463:
464: The following plugin-agnostic paths may be set in the
465: F<@sysconfdir@/sudo.conf> file.
466:
467: =over 16
468:
469: =item askpass
470:
471: The fully qualified path to a helper program used to read the user's
472: password when no terminal is available. This may be the case when
473: B<sudo> is executed from a graphical (as opposed to text-based)
474: application. The program specified by I<askpass> should display
475: the argument passed to it as the prompt and write the user's password
476: to the standard output. The value of I<askpass> may be overridden
477: by the C<SUDO_ASKPASS> environment variable.
478:
479: =item noexec
480:
481: The fully-qualified path to a shared library containing dummy
482: versions of the execv(), execve() and fexecve() library functions
483: that just return an error. This is used to implement the I<noexec>
484: functionality on systems that support C<LD_PRELOAD> or its equivalent.
485: Defaults to F<@noexec_file@>.
486:
487: =back
488:
489: =head1 RETURN VALUES
490:
491: Upon successful execution of a program, the exit status from B<sudo>
492: will simply be the exit status of the program that was executed.
493:
494: Otherwise, B<sudo> exits with a value of 1 if there is a
495: configuration/permission problem or if B<sudo> cannot execute the
496: given command. In the latter case the error string is printed to
497: the standard error. If B<sudo> cannot L<stat(2)> one or more entries
498: in the user's C<PATH>, an error is printed on stderr. (If the
499: directory does not exist or if it is not really a directory, the
500: entry is ignored and no error is printed.) This should not happen
501: under normal circumstances. The most common reason for L<stat(2)>
502: to return "permission denied" is if you are running an automounter
503: and one of the directories in your C<PATH> is on a machine that is
504: currently unreachable.
505:
506: =head1 SECURITY NOTES
507:
508: B<sudo> tries to be safe when executing external commands.
509:
510: To prevent command spoofing, B<sudo> checks "." and "" (both denoting
511: current directory) last when searching for a command in the user's
512: PATH (if one or both are in the PATH). Note, however, that the
513: actual C<PATH> environment variable is I<not> modified and is passed
514: unchanged to the program that B<sudo> executes.
515:
516: Please note that B<sudo> will normally only log the command it
517: explicitly runs. If a user runs a command such as C<sudo su> or
518: C<sudo sh>, subsequent commands run from that shell are not subject
519: to B<sudo>'s security policy. The same is true for commands that
520: offer shell escapes (including most editors). If I/O logging is
521: enabled, subsequent commands will have their input and/or output
522: logged, but there will not be traditional logs for those commands.
523: Because of this, care must be taken when giving users access to
524: commands via B<sudo> to verify that the command does not inadvertently
525: give the user an effective root shell. For more information, please
526: see the C<PREVENTING SHELL ESCAPES> section in L<sudoers(5)>.
527:
528: =head1 ENVIRONMENT
529:
530: B<sudo> utilizes the following environment variables. The security
531: policy has control over the content of the command's environment.
532:
533: =over 16
534:
535: =item C<EDITOR>
536:
537: Default editor to use in B<-e> (sudoedit) mode if neither C<SUDO_EDITOR>
538: nor C<VISUAL> is set
539:
540: =item C<MAIL>
541:
542: In B<-i> mode or when I<env_reset> is enabled in I<sudoers>, set
543: to the mail spool of the target user
544:
545: =item C<HOME>
546:
547: Set to the home directory of the target user if B<-i> or B<-H> are
548: specified, I<env_reset> or I<always_set_home> are set in I<sudoers>,
549: or when the B<-s> option is specified and I<set_home> is set in
550: I<sudoers>
551:
552: =item C<PATH>
553:
554: May be overridden by the security policy.
555:
556: =item C<SHELL>
557:
558: Used to determine shell to run with C<-s> option
559:
560: =item C<SUDO_ASKPASS>
561:
562: Specifies the path to a helper program used to read the password
563: if no terminal is available or if the C<-A> option is specified.
564:
565: =item C<SUDO_COMMAND>
566:
567: Set to the command run by sudo
568:
569: =item C<SUDO_EDITOR>
570:
571: Default editor to use in B<-e> (sudoedit) mode
572:
573: =item C<SUDO_GID>
574:
575: Set to the group ID of the user who invoked sudo
576:
577: =item C<SUDO_PROMPT>
578:
579: Used as the default password prompt
580:
581: =item C<SUDO_PS1>
582:
583: If set, C<PS1> will be set to its value for the program being run
584:
585: =item C<SUDO_UID>
586:
587: Set to the user ID of the user who invoked sudo
588:
589: =item C<SUDO_USER>
590:
591: Set to the login of the user who invoked sudo
592:
593: =item C<USER>
594:
595: Set to the target user (root unless the B<-u> option is specified)
596:
597: =item C<VISUAL>
598:
599: Default editor to use in B<-e> (sudoedit) mode if C<SUDO_EDITOR>
600: is not set
601:
602: =back
603:
604: =head1 FILES
605:
606: =over 24
607:
608: =item F<@sysconfdir@/sudo.conf>
609:
610: B<sudo> plugin and path configuration
611:
612: =back
613:
614: =head1 EXAMPLES
615:
616: Note: the following examples assume a properly configured security policy.
617:
618: To get a file listing of an unreadable directory:
619:
620: $ sudo ls /usr/local/protected
621:
622: To list the home directory of user yaz on a machine where the
623: file system holding ~yaz is not exported as root:
624:
625: $ sudo -u yaz ls ~yaz
626:
627: To edit the F<index.html> file as user www:
628:
629: $ sudo -u www vi ~www/htdocs/index.html
630:
631: To view system logs only accessible to root and users in the adm group:
632:
633: $ sudo -g adm view /var/log/syslog
634:
635: To run an editor as jim with a different primary group:
636:
637: $ sudo -u jim -g audio vi ~jim/sound.txt
638:
639: To shutdown a machine:
640:
641: $ sudo shutdown -r +15 "quick reboot"
642:
643: To make a usage listing of the directories in the /home
644: partition. Note that this runs the commands in a sub-shell
645: to make the C<cd> and file redirection work.
646:
647: $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE"
648:
649: =head1 SEE ALSO
650:
651: L<grep(1)>, L<su(1)>, L<stat(2)>,
652: L<login_cap(3)>,
653: L<passwd(5)>, L<sudoers(5)>, L<sudo_plugin(8)>, L<sudoreplay(8)>, L<visudo(8)>
654:
655: =head1 AUTHORS
656:
657: Many people have worked on B<sudo> over the years; this
658: version consists of code written primarily by:
659:
660: Todd C. Miller
661:
662: See the HISTORY file in the B<sudo> distribution or visit
663: http://www.sudo.ws/sudo/history.html for a short history
664: of B<sudo>.
665:
666: =head1 CAVEATS
667:
668: There is no easy way to prevent a user from gaining a root shell
669: if that user is allowed to run arbitrary commands via B<sudo>.
670: Also, many programs (such as editors) allow the user to run commands
671: via shell escapes, thus avoiding B<sudo>'s checks. However, on
672: most systems it is possible to prevent shell escapes with the
673: L<sudoers(5)> module's I<noexec> functionality.
674:
675: It is not meaningful to run the C<cd> command directly via sudo, e.g.,
676:
677: $ sudo cd /usr/local/protected
678:
679: since when the command exits the parent process (your shell) will
680: still be the same. Please see the EXAMPLES section for more information.
681:
682: Running shell scripts via B<sudo> can expose the same kernel bugs that
683: make setuid shell scripts unsafe on some operating systems (if your OS
684: has a /dev/fd/ directory, setuid shell scripts are generally safe).
685:
686: =head1 BUGS
687:
688: If you feel you have found a bug in B<sudo>, please submit a bug report
689: at http://www.sudo.ws/sudo/bugs/
690:
691: =head1 SUPPORT
692:
693: Limited free support is available via the sudo-users mailing list,
694: see http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or
695: search the archives.
696:
697: =head1 DISCLAIMER
698:
699: B<sudo> is provided ``AS IS'' and any express or implied warranties,
700: including, but not limited to, the implied warranties of merchantability
701: and fitness for a particular purpose are disclaimed. See the LICENSE
702: file distributed with B<sudo> or http://www.sudo.ws/sudo/license.html
703: for complete details.
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