.\" dpkg manual page - start-stop-daemon(8) .\" .\" Copyright © 1999 Klee Dienes .\" Copyright © 1999 Ben Collins .\" Copyright © 2000-2001 Wichert Akkerman .\" Copyright © 2002-2003 Adam Heath .\" Copyright © 2004 Scott James Remnant .\" Copyright © 2008-2015 Guillem Jover .\" .\" This is free software; you can redistribute it and/or modify .\" it under the terms of the GNU General Public License as published by .\" the Free Software Foundation; either version 2 of the License, or .\" (at your option) any later version. .\" .\" This is distributed in the hope that it will be useful, .\" but WITHOUT ANY WARRANTY; without even the implied warranty of .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the .\" GNU General Public License for more details. .\" .\" You should have received a copy of the GNU General Public License .\" along with this program. If not, see . . .TH start\-stop\-daemon 8 "%RELEASE_DATE%" "%VERSION%" "dpkg suite" .nh .SH NAME start\-stop\-daemon \- start and stop system daemon programs . .SH SYNOPSIS .B start\-stop\-daemon .RI [ option "...] " command . .SH DESCRIPTION .B start\-stop\-daemon is used to control the creation and termination of system-level processes. Using one of the matching options, \fBstart\-stop\-daemon\fP can be configured to find existing instances of a running process. .PP Note: unless .B \-\-pid or .B \-\-pidfile are specified, .B start\-stop\-daemon behaves similar to .BR killall (1). .B start\-stop\-daemon will scan the process table looking for any processes which match the process name, parent pid, uid, and/or gid (if specified). Any matching process will prevent .BR \-\-start from starting the daemon. All matching processes will be sent the TERM signal (or the one specified via \fB\-\-signal\fP or \fB\-\-retry\fP) if .BR \-\-stop is specified. For daemons which have long-lived children which need to live through a .BR \-\-stop , you must specify a pidfile. . .SH COMMANDS .TP .BR \-S ", " \-\-start " [" \-\- "] \fIarguments\fP" Check for the existence of a specified process. If such a process exists, .B start\-stop\-daemon does nothing, and exits with error status 1 (0 if .BR \-\-oknodo is specified). If such a process does not exist, it starts an instance, using either the executable specified by .B \-\-exec or, if specified, by .BR \-\-startas . Any arguments given after .BR \-\- on the command line are passed unmodified to the program being started. .TP .BR \-K ", " \-\-stop Checks for the existence of a specified process. If such a process exists, .B start\-stop\-daemon sends it the signal specified by .BR \-\-signal , and exits with error status 0. If such a process does not exist, .B start\-stop\-daemon exits with error status 1 (0 if .BR \-\-oknodo is specified). If .B \-\-retry is specified, then .B start\-stop\-daemon will check that the process(es) have terminated. .TP .BR \-T ", " \-\-status Check for the existence of a specified process, and returns an exit status code, according to the LSB Init Script Actions (since version 1.16.1). .TP .BR \-H ", " \-\-help Show usage information and exit. .TP .BR \-V ", " \-\-version Show the program version and exit. . .SH OPTIONS .SS Matching options .TP .BR \-\-pid " \fIpid\fP" Check for a process with the specified \fIpid\fP (since version 1.17.6). The \fIpid\fP must be a number greater than 0. .TP .BR \-\-ppid " \fIppid\fP" Check for a process with the specified parent pid \fIppid\fP (since version 1.17.7). The \fIppid\fP must be a number greater than 0. .TP .BR \-p ", " \-\-pidfile " \fIpid-file\fP" Check whether a process has created the file \fIpid-file\fP. .IP Note: using this matching option alone might cause unintended processes to be acted on, if the old process terminated without being able to remove the \fIpid-file\fP. .IP \fBWarning:\fP Using this match option alone with a daemon that writes the pidfile as an unprivileged user is a security risk, because if the daemon gets compromised the contents of the pidfile cannot be trusted, and then a privileged runner (such as an init script executed as root) would end up acting on any system process. .TP .BR \-x ", " \-\-exec " \fIexecutable\fP" Check for processes that are instances of this \fIexecutable\fP. The \fIexecutable\fP argument should be an absolute pathname. Note: this might not work as intended with interpreted scripts, as the executable will point to the interpreter. Take into account processes running from inside a chroot will also be matched, so other match restrictions might be needed. .TP .BR \-n ", " \-\-name " \fIprocess-name\fP" Check for processes with the name \fIprocess-name\fP. The \fIprocess-name\fP is usually the process filename, but it could have been changed by the process itself. Note: on most systems this information is retrieved from the process comm name from the kernel, which tends to have a relatively short length limit (assuming more than 15 characters is non-portable). .TP .BR \-u ", " \-\-user " \fIusername\fP|\fIuid\fP Check for processes owned by the user specified by \fIusername\fP or \fIuid\fP. Note: using this matching option alone will cause all processes matching the user to be acted on. . .SS Generic options .TP .BR \-g ", " \-\-group " \fIgroup\fP|\fIgid\fP" Change to \fIgroup\fP or \fIgid\fP when starting the process. .TP .BR \-s ", " \-\-signal " \fIsignal\fP" With .BR \-\-stop , specifies the signal to send to processes being stopped (default TERM). .TP .BR \-R ", " \-\-retry " \fItimeout\fP|\fIschedule\fP" With .BR \-\-stop , specifies that .B start\-stop\-daemon is to check whether the process(es) do finish. It will check repeatedly whether any matching processes are running, until none are. If the processes do not exit it will then take further action as determined by the schedule. If .I timeout is specified instead of .IR schedule , then the schedule .IB signal / timeout /KILL/ timeout is used, where .I signal is the signal specified with .BR \-\-signal . .I schedule is a list of at least two items separated by slashes .RB ( / ); each item may be .BI \- signal-number or [\fB\-\fP]\fIsignal-name\fP, which means to send that signal, or .IR timeout , which means to wait that many seconds for processes to exit, or .BR forever , which means to repeat the rest of the schedule forever if necessary. If the end of the schedule is reached and .BR forever is not specified, then .B start\-stop\-daemon exits with error status 2. If a schedule is specified, then any signal specified with .B \-\-signal is ignored. .TP .BR \-a ", " \-\-startas " \fIpathname\fP" With .BR \-\-start , start the process specified by .IR pathname . If not specified, defaults to the argument given to .BR \-\-exec . .TP .BR \-t ", " \-\-test Print actions that would be taken and set appropriate return value, but take no action. .TP .BR \-o ", " \-\-oknodo Return exit status 0 instead of 1 if no actions are (would be) taken. .TP .BR \-q ", " \-\-quiet Do not print informational messages; only display error messages. .TP .BR \-c ", " \-\-chuid " \fIusername\fR|\fIuid\fP[\fB:\fP\fIgroup\fR|\fIgid\fP]" Change to this username/uid before starting the process. You can also specify a group by appending a .BR : , then the group or gid in the same way as you would for the \fBchown\fP(1) command (\fIuser\fP\fB:\fP\fIgroup\fP). If a user is specified without a group, the primary GID for that user is used. When using this option you must realize that the primary and supplemental groups are set as well, even if the .B \-\-group option is not specified. The .B \-\-group option is only for groups that the user isn't normally a member of (like adding per process group membership for generic users like .BR nobody ). .TP .BR \-r ", " \-\-chroot " \fIroot\fP" Chdir and chroot to .I root before starting the process. Please note that the pidfile is also written after the chroot. .TP .BR \-d ", " \-\-chdir " \fIpath\fP" Chdir to .I path before starting the process. This is done after the chroot if the \fB\-r\fP|\fB\-\-chroot\fP option is set. When not specified, .B start\-stop\-daemon will chdir to the root directory before starting the process. .TP .BR \-b ", " \-\-background Typically used with programs that don't detach on their own. This option will force .B start\-stop\-daemon to fork before starting the process, and force it into the background. .B Warning: start\-stop\-daemon cannot check the exit status if the process fails to execute for .B any reason. This is a last resort, and is only meant for programs that either make no sense forking on their own, or where it's not feasible to add the code for them to do this themselves. .TP .BR \-C ", " \-\-no\-close Do not close any file descriptor when forcing the daemon into the background (since version 1.16.5). Used for debugging purposes to see the process output, or to redirect file descriptors to log the process output. Only relevant when using \fB\-\-background\fP. .TP .BR \-N ", " \-\-nicelevel " \fIint\fP" This alters the priority of the process before starting it. .TP .BR \-P ", " \-\-procsched " \fIpolicy\fP\fB:\fP\fIpriority\fP" This alters the process scheduler policy and priority of the process before starting it (since version 1.15.0). The priority can be optionally specified by appending a \fB:\fP followed by the value. The default \fIpriority\fP is 0. The currently supported policy values are \fBother\fP, \fBfifo\fP and \fBrr\fP. .TP .BR \-I ", " \-\-iosched " \fIclass\fP\fB:\fP\fIpriority\fP" This alters the IO scheduler class and priority of the process before starting it (since version 1.15.0). The priority can be optionally specified by appending a \fB:\fP followed by the value. The default \fIpriority\fP is 4, unless \fIclass\fP is \fBidle\fP, then \fIpriority\fP will always be 7. The currently supported values for \fIclass\fP are \fBidle\fP, \fBbest-effort\fP and \fBreal-time\fP. .TP .BR \-k ", " \-\-umask " \fImask\fP" This sets the umask of the process before starting it (since version 1.13.22). .TP .BR \-m ", " \-\-make\-pidfile Used when starting a program that does not create its own pid file. This option will make .B start\-stop\-daemon create the file referenced with .B \-\-pidfile and place the pid into it just before executing the process. Note, the file will only be removed when stopping the program if \fB\-\-remove\-pidfile\fP is used. .B Note: This feature may not work in all cases. Most notably when the program being executed forks from its main process. Because of this, it is usually only useful when combined with the .B \-\-background option. .TP .B \-\-remove\-pidfile Used when stopping a program that does not remove its own pid file (since version 1.17.19). This option will make .B start\-stop\-daemon remove the file referenced with .B \-\-pidfile after terminating the process. .TP .BR \-v ", " \-\-verbose Print verbose informational messages. . .SH EXIT STATUS .TP .B 0 The requested action was performed. If .B \-\-oknodo was specified, it's also possible that nothing had to be done. This can happen when .B \-\-start was specified and a matching process was already running, or when .B \-\-stop was specified and there were no matching processes. .TP .B 1 If .B \-\-oknodo was not specified and nothing was done. .TP .B 2 If .B \-\-stop and .B \-\-retry were specified, but the end of the schedule was reached and the processes were still running. .TP .B 3 Any other error. .PP When using the \fB\-\-status\fP command, the following status codes are returned: .TP .B 0 Program is running. .TP .B 1 Program is not running and the pid file exists. .TP .B 3 Program is not running. .TP .B 4 Unable to determine program status. . .SH EXAMPLE Start the \fBfood\fP daemon, unless one is already running (a process named food, running as user food, with pid in food.pid): .IP .nf start\-stop\-daemon \-\-start \-\-oknodo \-\-user food \-\-name food \\ \-\-pidfile /run/food.pid \-\-startas /usr/sbin/food \\ \-\-chuid food \-\- \-\-daemon .fi .PP Send \fBSIGTERM\fP to \fBfood\fP and wait up to 5 seconds for it to stop: .IP .nf start\-stop\-daemon \-\-stop \-\-oknodo \-\-user food \-\-name food \\ \-\-pidfile /run/food.pid \-\-retry 5 .fi .PP Demonstration of a custom schedule for stopping \fBfood\fP: .IP .nf start\-stop\-daemon \-\-stop \-\-oknodo \-\-user food \-\-name food \\ \-\-pidfile /run/food.pid \-\-retry=TERM/30/KILL/5 .fi