start-stop-daemon is used to control the creation and termination
of system-level processes. Using one of the matching options,
start-stop-daemon can be configured to find existing instances of
a running process.
Note: unless --pid or --pidfile are specified, start-stop-daemon
behaves similar to killall(1). 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 --start from starting the daemon. All
matching processes will be sent the TERM signal (or the one
specified via --signal or --retry) if --stop is specified. For
daemons which have long-lived children which need to live through
a --stop, you must specify a pidfile.
-S, --start [--] arguments
Check for the existence of a specified process. If such a
process exists, start-stop-daemon does nothing, and exits
with error status 1 (0 if --oknodo is specified). If such
a process does not exist, it starts an instance, using
either the executable specified by --exec or, if
specified, by --startas. Any arguments given after -- on
the command line are passed unmodified to the program
Checks for the existence of a specified process. If such
a process exists, start-stop-daemon sends it the signal
specified by --signal, and exits with error status 0. If
such a process does not exist, start-stop-daemon exits
with error status 1 (0 if --oknodo is specified). If
--retry is specified, then start-stop-daemon will check
that the process(es) have terminated.
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).
Show usage information and exit.
Show the program version and exit.
Matching options--pid pid
Check for a process with the specified pid (since version
1.17.6). The pid must be a number greater than 0.
Check for a process with the specified parent pid ppid
(since version 1.17.7). The ppid must be a number greater
-p, --pidfile pid-file
Check whether a process has created the file pid-file.
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 pid-file.
Warning: using this match option with a world-writable
pidfile or using it alone with a daemon that writes the
pidfile as an unprivileged (non-root) user will be refused
with an error (since version 1.19.3) as this is a security
risk, because either any user can write to it, or 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. Using /dev/null is exempt from these
-x, --exec executable
Check for processes that are instances of this executable.
The executable 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
-n, --name process-name
Check for processes with the name process-name. The
process-name 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).
-u, --user username|uid
Check for processes owned by the user specified by
username or uid. Note: using this matching option alone
will cause all processes matching the user to be acted on.
Generic options-g, --group group|gid
Change to group or gid when starting the process.
-s, --signal signal
With --stop, specifies the signal to send to processes
being stopped (default TERM).
-R, --retry timeout|schedule
With --stop, specifies that 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 timeout is specified instead of schedule, then the
schedule signal/timeout/KILL/timeout is used, where signal
is the signal specified with --signal.
schedule is a list of at least two items separated by
slashes (/); each item may be -signal-number or [-]signal-name, which means to send that signal, or timeout, which
means to wait that many seconds for processes to exit, or
forever, which means to repeat the rest of the schedule
forever if necessary.
If the end of the schedule is reached and forever is not
specified, then start-stop-daemon exits with error status
2. If a schedule is specified, then any signal specified
with --signal is ignored.
-a, --startas pathname
With --start, start the process specified by pathname. If
not specified, defaults to the argument given to --exec.
Print actions that would be taken and set appropriate
return value, but take no action.
Return exit status 0 instead of 1 if no actions are (would
Do not print informational messages; only display error
-c, --chuid username|uid[:group|gid]
Change to this username/uid before starting the process.
You can also specify a group by appending a :, then the
group or gid in the same way as you would for the chown(1)
command (user:group). 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 --group
option is not specified. The --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
-r, --chroot root
Chdir and chroot to root before starting the process.
Please note that the pidfile is also written after the
-d, --chdir path
Chdir to path before starting the process. This is done
after the chroot if the -r|--chroot option is set. When
not specified, start-stop-daemon will chdir to the root
directory before starting the process.
Typically used with programs that don't detach on their
own. This option will force start-stop-daemon to fork
before starting the process, and force it into the
background. Warning: start-stop-daemon cannot check the
exit status if the process fails to execute for 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
Wait for the background process to send a readiness
notification before considering the service started (since
version 1.19.3). This implements parts of the systemd
readiness procotol, as specified in the sd_notify(3) man
page. The following variables are supported:
The program is ready to give service, so we can
The program requests to extend the timeout by
number microseconds. This will reset the current
timeout to the specified value.
The program is exiting with an error. Do the same
and print the user-friendly string for the errno
Set a timeout for the --notify-await option (since version
1.19.3). When the timeout is reached, start-stop-daemon
will exit with an error code, and no readiness
notification will be awaited. The default is 60 seconds.
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 --background.
-N, --nicelevel int
This alters the priority of the process before starting
-P, --procsched policy:priority
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 :
followed by the value. The default priority is 0. The
currently supported policy values are other, fifo and rr.
-I, --iosched class:priority
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 :
followed by the value. The default priority is 4, unless
class is idle, then priority will always be 7. The
currently supported values for class are idle, best-effort
-k, --umask mask
This sets the umask of the process before starting it
(since version 1.13.22).
Used when starting a program that does not create its own
pid file. This option will make start-stop-daemon create
the file referenced with --pidfile and place the pid into
it just before executing the process. Note, the file will
only be removed when stopping the program if
--remove-pidfile is used. 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 --background
Used when stopping a program that does not remove its own
pid file (since version 1.17.19). This option will make
start-stop-daemon remove the file referenced with
--pidfile after terminating the process.
Print verbose informational messages.
0 The requested action was performed. If --oknodo was
specified, it's also possible that nothing had to be done.
This can happen when --start was specified and a matching
process was already running, or when --stop was specified
and there were no matching processes.
1 If --oknodo was not specified and nothing was done.
2 If --stop and --retry were specified, but the end of the
schedule was reached and the processes were still running.
3 Any other error.
When using the --status command, the following status codes are
0 Program is running.
1 Program is not running and the pid file exists.
3 Program is not running.
4 Unable to determine program status.
Start the food daemon, unless one is already running (a process
named food, running as user food, with pid in food.pid):
start-stop-daemon --start --oknodo --user food --name food \
--pidfile /run/food.pid --startas /usr/sbin/food \
--chuid food -- --daemon
Send SIGTERM to food and wait up to 5 seconds for it to stop:
start-stop-daemon --stop --oknodo --user food --name food \
--pidfile /run/food.pid --retry 5
Demonstration of a custom schedule for stopping food:
start-stop-daemon --stop --oknodo --user food --name food \
--pidfile /run/food.pid --retry=TERM/30/KILL/5
This page is part of the dpkg (Debian Package Manager) project.
Information about the project can be found at
⟨https://wiki.debian.org/Teams/Dpkg/⟩. If you have a bug report
for this manual page, see
page was obtained from the project's upstream Git repository
⟨https://salsa.debian.org/dpkg-team/dpkg.git⟩ on 2021-08-27. (At
that time, the date of the most recent commit that was found in
the repository was 2021-06-17.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
1.19.6-2-g6e42d5 2019-03-25 start-stop-daemon(8)