1 .\" dpkg manual page - start-stop-daemon(8)
2 .\"
3 .\" Copyright © 1999 Klee Dienes <klee@mit.edu>
4 .\" Copyright © 1999 Ben Collins <bcollins@debian.org>
5 .\" Copyright © 2000-2001 Wichert Akkerman <wakkerma@debian.org>
6 .\" Copyright © 2002-2003 Adam Heath <doogie@debian.org>
7 .\" Copyright © 2004 Scott James Remnant <keybuk@debian.org>
8 .\" Copyright © 2008-2016, 2018 Guillem Jover <guillem@debian.org>
9 .\"
10 .\" This is free software; you can redistribute it and/or modify
11 .\" it under the terms of the GNU General Public License as published by
12 .\" the Free Software Foundation; either version 2 of the License, or
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15 .\" This is distributed in the hope that it will be useful,
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17 .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 .\" GNU General Public License for more details.
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21 .\" along with this program. If not, see <https://www.gnu.org/licenses/>.
22 .
23 .TH start\-stop\-daemon 8 "%RELEASE_DATE%" "%VERSION%" "dpkg suite"
24 .nh
25 .SH NAME
26 start\-stop\-daemon \- start and stop system daemon programs
27 .
28 .SH SYNOPSIS
29 .B start\-stop\-daemon
30 .RI [ option "...] " command
31 .
32 .SH DESCRIPTION
33 .B start\-stop\-daemon
34 is used to control the creation and termination of system-level processes.
35 Using one of the matching options, \fBstart\-stop\-daemon\fP
36 can be configured to find existing instances of a running process.
37 .PP
38 Note: unless
39 .B \-\-pid
40 or
41 .B \-\-pidfile
42 are specified,
43 .B start\-stop\-daemon
44 behaves similar to
45 .BR killall (1).
46 .B start\-stop\-daemon
47 will scan the process table looking for any processes which
48 match the process name, parent pid, uid, and/or gid (if specified). Any
49 matching process will prevent
50 .BR \-\-start
51 from starting the daemon. All matching processes will be sent the TERM
52 signal (or the one specified via \fB\-\-signal\fP or \fB\-\-retry\fP) if
53 .BR \-\-stop
54 is specified. For daemons which have long-lived children
55 which need to live through a
56 .BR \-\-stop ,
57 you must specify a pidfile.
58 .
59 .SH COMMANDS
60 .TP
61 .BR \-S ", " \-\-start " [" \-\- "] \fIarguments\fP"
62 Check for the existence of a specified process.
63 If such a process exists,
64 .B start\-stop\-daemon
65 does nothing, and exits with error status 1 (0 if
66 .BR \-\-oknodo
67 is specified).
68 If such a process does not exist, it starts an
69 instance, using either the executable specified by
70 .B \-\-exec
71 or, if specified, by
72 .BR \-\-startas .
73 Any arguments given after
74 .BR \-\-
75 on the command line are passed unmodified to the program being
76 started.
77 .TP
78 .BR \-K ", " \-\-stop
79 Checks for the existence of a specified process.
80 If such a process exists,
81 .B start\-stop\-daemon
82 sends it the signal specified by
83 .BR \-\-signal ,
84 and exits with error status 0.
85 If such a process does not exist,
86 .B start\-stop\-daemon
87 exits with error status 1
88 (0 if
89 .BR \-\-oknodo
90 is specified). If
91 .B \-\-retry
92 is specified, then
93 .B start\-stop\-daemon
94 will check that the process(es) have terminated.
95 .TP
96 .BR \-T ", " \-\-status
97 Check for the existence of a specified process, and returns an exit status
98 code, according to the LSB Init Script Actions (since version 1.16.1).
99 .TP
100 .BR \-H ", " \-\-help
101 Show usage information and exit.
102 .TP
103 .BR \-V ", " \-\-version
104 Show the program version and exit.
105 .
106 .SH OPTIONS
107 .SS Matching options
108 .TP
109 .BR \-\-pid " \fIpid\fP"
110 Check for a process with the specified \fIpid\fP (since version 1.17.6).
111 The \fIpid\fP must be a number greater than 0.
112 .TP
113 .BR \-\-ppid " \fIppid\fP"
114 Check for a process with the specified parent pid \fIppid\fP
115 (since version 1.17.7).
116 The \fIppid\fP must be a number greater than 0.
117 .TP
118 .BR \-p ", " \-\-pidfile " \fIpid-file\fP"
119 Check whether a process has created the file \fIpid-file\fP.
120 .IP
121 Note: using this matching option alone might cause unintended processes to
122 be acted on, if the old process terminated without being able to remove the
123 \fIpid-file\fP.
124 .IP
125 \fBWarning:\fP using this match option with a world-writable pidfile or using
126 it alone with a daemon that writes the pidfile as an unprivileged (non-root)
127 user will be refused with an error (since version 1.19.3) as this is a
128 security risk, because either any user can write to it, or if the daemon
129 gets compromised, the contents of the pidfile cannot be trusted, and then
130 a privileged runner (such as an init script executed as root) would end up
131 acting on any system process.
132 Using \fI/dev/null\fP is exempt from these checks.
133 .TP
134 .BR \-x ", " \-\-exec " \fIexecutable\fP"
135 Check for processes that are instances of this \fIexecutable\fP. The
136 \fIexecutable\fP argument should be an absolute pathname. Note: this might
137 not work as intended with interpreted scripts, as the executable will point
138 to the interpreter. Take into account processes running from inside a chroot
139 will also be matched, so other match restrictions might be needed.
140 .TP
141 .BR \-n ", " \-\-name " \fIprocess-name\fP"
142 Check for processes with the name \fIprocess-name\fP. The \fIprocess-name\fP
143 is usually the process filename, but it could have been changed by the
144 process itself. Note: on most systems this information is retrieved from
145 the process comm name from the kernel, which tends to have a relatively
146 short length limit (assuming more than 15 characters is non-portable).
147 .TP
148 .BR \-u ", " \-\-user " \fIusername\fP|\fIuid\fP
149 Check for processes owned by the user specified by \fIusername\fP or
150 \fIuid\fP. Note: using this matching option alone will cause all processes
151 matching the user to be acted on.
152 .
153 .SS Generic options
154 .TP
155 .BR \-g ", " \-\-group " \fIgroup\fP|\fIgid\fP"
156 Change to \fIgroup\fP or \fIgid\fP when starting the process.
157 .TP
158 .BR \-s ", " \-\-signal " \fIsignal\fP"
159 With
160 .BR \-\-stop ,
161 specifies the signal to send to processes being stopped (default TERM).
162 .TP
163 .BR \-R ", " \-\-retry " \fItimeout\fP|\fIschedule\fP"
164 With
165 .BR \-\-stop ,
166 specifies that
167 .B start\-stop\-daemon
168 is to check whether the process(es)
169 do finish. It will check repeatedly whether any matching processes
170 are running, until none are. If the processes do not exit it will
171 then take further action as determined by the schedule.
172
173 If
174 .I timeout
175 is specified instead of
176 .IR schedule ,
177 then the schedule
178 .IB signal / timeout /KILL/ timeout
179 is used, where
180 .I signal
181 is the signal specified with
182 .BR \-\-signal .
183
184 .I schedule
185 is a list of at least two items separated by slashes
186 .RB ( / );
187 each item may be
188 .BI \- signal-number
189 or [\fB\-\fP]\fIsignal-name\fP,
190 which means to send that signal,
191 or
192 .IR timeout ,
193 which means to wait that many seconds for processes to
194 exit,
195 or
196 .BR forever ,
197 which means to repeat the rest of the schedule forever if
198 necessary.
199
200 If the end of the schedule is reached and
201 .BR forever
202 is not specified, then
203 .B start\-stop\-daemon
204 exits with error status 2.
205 If a schedule is specified, then any signal specified
206 with
207 .B \-\-signal
208 is ignored.
209 .TP
210 .BR \-a ", " \-\-startas " \fIpathname\fP"
211 With
212 .BR \-\-start ,
213 start the process specified by
214 .IR pathname .
215 If not specified, defaults to the argument given to
216 .BR \-\-exec .
217 .TP
218 .BR \-t ", " \-\-test
219 Print actions that would be taken and set appropriate return value,
220 but take no action.
221 .TP
222 .BR \-o ", " \-\-oknodo
223 Return exit status 0 instead of 1 if no actions are (would be) taken.
224 .TP
225 .BR \-q ", " \-\-quiet
226 Do not print informational messages; only display error messages.
227 .TP
228 .BR \-c ", " \-\-chuid " \fIusername\fR|\fIuid\fP[\fB:\fP\fIgroup\fR|\fIgid\fP]"
229 Change to this username/uid before starting the process. You can also
230 specify a group by appending a
231 .BR : ,
232 then the group or gid in the same way
233 as you would for the \fBchown\fP(1) command (\fIuser\fP\fB:\fP\fIgroup\fP).
234 If a user is specified without a group, the primary GID for that user is used.
235 When using this option
236 you must realize that the primary and supplemental groups are set as well,
237 even if the
238 .B \-\-group
239 option is not specified. The
240 .B \-\-group
241 option is only for
242 groups that the user isn't normally a member of (like adding per process
243 group membership for generic users like
244 .BR nobody ).
245 .TP
246 .BR \-r ", " \-\-chroot " \fIroot\fP"
247 Chdir and chroot to
248 .I root
249 before starting the process. Please note that the pidfile is also written
250 after the chroot.
251 .TP
252 .BR \-d ", " \-\-chdir " \fIpath\fP"
253 Chdir to
254 .I path
255 before starting the process. This is done after the chroot if the
256 \fB\-r\fP|\fB\-\-chroot\fP option is set. When not specified,
257 .B start\-stop\-daemon
258 will chdir to the root directory before starting the process.
259 .TP
260 .BR \-b ", " \-\-background
261 Typically used with programs that don't detach on their own. This option
262 will force
263 .B start\-stop\-daemon
264 to fork before starting the process, and force it into the background.
265 .B Warning: start\-stop\-daemon
266 cannot check the exit status if the process fails to execute for
267 .B any
268 reason. This is a last resort, and is only meant for programs that either
269 make no sense forking on their own, or where it's not feasible to add the
270 code for them to do this themselves.
271 .TP
272 .BR \-\-notify\-await
273 Wait for the background process to send a readiness notification before
274 considering the service started (since version 1.19.3).
275 This implements parts of the systemd readiness procotol, as specified
276 in the \fBsd_notify\fP(3) man page.
277 The following variables are supported:
278 .RS
279 .TP
280 .B READY=1
281 The program is ready to give service, so we can exit safely.
282 .TP
283 .BI EXTEND_TIMEOUT_USEC= number
284 The program requests to extend the timeout by \fInumber\fP microseconds.
285 This will reset the current timeout to the specified value.
286 .TP
287 .BI ERRNO= number
288 The program is exiting with an error.
289 Do the same and print the user-friendly string for the \fBerrno\fP value.
290 .RE
291 .
292 .TP
293 .BI \-\-notify\-timeout timeout
294 Set a timeout for the \fB\-\-notify\-await\fP option (since version 1.19.3).
295 When the timeout is reached, \fBstart\-stop\-daemon\fP will exit with an
296 error code, and no readiness notification will be awaited.
297 The default is \fB60\fP seconds.
298 .TP
299 .BR \-C ", " \-\-no\-close
300 Do not close any file descriptor when forcing the daemon into the background
301 (since version 1.16.5).
302 Used for debugging purposes to see the process output, or to redirect file
303 descriptors to log the process output.
304 Only relevant when using \fB\-\-background\fP.
305 .TP
306 .BR \-N ", " \-\-nicelevel " \fIint\fP"
307 This alters the priority of the process before starting it.
308 .TP
309 .BR \-P ", " \-\-procsched " \fIpolicy\fP\fB:\fP\fIpriority\fP"
310 This alters the process scheduler policy and priority of the process before
311 starting it (since version 1.15.0).
312 The priority can be optionally specified by appending a \fB:\fP
313 followed by the value. The default \fIpriority\fP is 0. The currently
314 supported policy values are \fBother\fP, \fBfifo\fP and \fBrr\fP.
315 .TP
316 .BR \-I ", " \-\-iosched " \fIclass\fP\fB:\fP\fIpriority\fP"
317 This alters the IO scheduler class and priority of the process before starting
318 it (since version 1.15.0).
319 The priority can be optionally specified by appending a \fB:\fP followed
320 by the value. The default \fIpriority\fP is 4, unless \fIclass\fP is \fBidle\fP,
321 then \fIpriority\fP will always be 7. The currently supported values for
322 \fIclass\fP are \fBidle\fP, \fBbest-effort\fP and \fBreal-time\fP.
323 .TP
324 .BR \-k ", " \-\-umask " \fImask\fP"
325 This sets the umask of the process before starting it (since version 1.13.22).
326 .TP
327 .BR \-m ", " \-\-make\-pidfile
328 Used when starting a program that does not create its own pid file. This
329 option will make
330 .B start\-stop\-daemon
331 create the file referenced with
332 .B \-\-pidfile
333 and place the pid into it just before executing the process. Note, the
334 file will only be removed when stopping the program if
335 \fB\-\-remove\-pidfile\fP is used.
336 .B Note:
337 This feature may not work in all cases. Most notably when the program
338 being executed forks from its main process. Because of this, it is usually
339 only useful when combined with the
340 .B \-\-background
341 option.
342 .TP
343 .B \-\-remove\-pidfile
344 Used when stopping a program that does not remove its own pid file
345 (since version 1.17.19).
346 This option will make
347 .B start\-stop\-daemon
348 remove the file referenced with
349 .B \-\-pidfile
350 after terminating the process.
351 .TP
352 .BR \-v ", " \-\-verbose
353 Print verbose informational messages.
354 .
355 .SH EXIT STATUS
356 .TP
357 .B 0
358 The requested action was performed. If
359 .B \-\-oknodo
360 was specified, it's also possible that nothing had to be done.
361 This can happen when
362 .B \-\-start
363 was specified and a matching process was already running, or when
364 .B \-\-stop
365 was specified and there were no matching processes.
366 .TP
367 .B 1
368 If
369 .B \-\-oknodo
370 was not specified and nothing was done.
371 .TP
372 .B 2
373 If
374 .B \-\-stop
375 and
376 .B \-\-retry
377 were specified, but the end of the schedule was reached and the processes were
378 still running.
379 .TP
380 .B 3
381 Any other error.
382 .PP
383 When using the \fB\-\-status\fP command, the following status codes are
384 returned:
385 .TP
386 .B 0
387 Program is running.
388 .TP
389 .B 1
390 Program is not running and the pid file exists.
391 .TP
392 .B 3
393 Program is not running.
394 .TP
395 .B 4
396 Unable to determine program status.
397 .
398 .SH EXAMPLE
399 Start the \fBfood\fP daemon, unless one is already running (a process named
400 food, running as user food, with pid in food.pid):
401 .IP
402 .nf
403 start\-stop\-daemon \-\-start \-\-oknodo \-\-user food \-\-name food \\
404 \-\-pidfile /run/food.pid \-\-startas /usr/sbin/food \\
405 \-\-chuid food \-\- \-\-daemon
406 .fi
407 .PP
408 Send \fBSIGTERM\fP to \fBfood\fP and wait up to 5 seconds for it to stop:
409 .IP
410 .nf
411 start\-stop\-daemon \-\-stop \-\-oknodo \-\-user food \-\-name food \\
412 \-\-pidfile /run/food.pid \-\-retry 5
413 .fi
414 .PP
415 Demonstration of a custom schedule for stopping \fBfood\fP:
416 .IP
417 .nf
418 start\-stop\-daemon \-\-stop \-\-oknodo \-\-user food \-\-name food \\
419 \-\-pidfile /run/food.pid \-\-retry=TERM/30/KILL/5
420 .fi
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