start-stop-daemon - start and stop system daemon programs
is used to control the creation and termination of
system-level processes. Using one of the matching options,
can be configured to find existing instances of a
Note: unless --pidfile
is specified, start-stop-daemon
similar to killall(1)
will scan the process
table looking for any processes which match the process name, uid, and/or gid
(if specified). Any matching process will prevent --start
the daemon. All matching processes will be sent the TERM signal (or the one
specified via --signal
) if --stop
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
- -K, --stop
- 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
- -T, --status
- Check for the existence of a specified process, and returns
an exit status code, according to the LSB Init Script Actions.
- -H, --help
- Show usage information and exit.
- -V, --version
- Show the program version and exit.
- -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.
- -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 needed.
- -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
- -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.
- -g, --group group|gid
- Change to group or gid when starting the
- -s, --signal signal
- With --stop, specifies the signal to send to
processes being stopped (default TERM).
- -R, --retry
- 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
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
- -t, --test
- Print actions that would be taken and set appropriate
return value, but take no action.
- -o, --oknodo
- Return exit status 0 instead of 1 if no actions are (would
- -q, --quiet
- Do not print informational messages; only display error
- -c, --chuid
- 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' 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 nobody).
- -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.
- -b, --background
- 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 this themselves.
- -C, --no-close
- Do not close any file descriptor when forcing the daemon
into the background. 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
- This alters the process scheduler policy and priority of
the process before starting it. 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
- -I, --iosched
- This alters the IO scheduler class and priority of the
process before starting it. 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 and real-time.
- -k, --umask mask
- This sets the umask of the process before starting it.
- -m, --make-pidfile
- 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 not be removed when stopping
the program. 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
- -v, --verbose
- Print verbose informational messages.
- 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
- If --oknodo was not specified and nothing was
- If --stop and --retry were specified, but the
end of the schedule was reached and the processes were still running.
- Any other error.
When using the --status
command, the following status codes are returned:
- Program is running.
- Program is not running and the pid file exists.
- Program is not running.
- 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
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