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 --pid
behaves similar to killall(1)
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
) if --stop
is specified. For daemons
which have long-lived children which need to live through a --stop
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 being started.
- -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.
- --pid pid
- Check for a process with the specified pid. The pid must be
a number greater than 0.
- --ppid ppid
- Check for a process with the specified ppid (parent pid). The
ppid must be a number greater than 0.
- -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
- -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
- -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 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.
- -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 be) taken.
- -q, --quiet
- Do not print informational messages; only display error messages.
- -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 chroot.
- -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
- -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
- -N, --nicelevel int
- This alters the priority of the process before starting it.
- -P, --procsched policy:priority
- 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 and
- -I, --iosched class:priority
- 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 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 option.
- Used when stopping a program that does not remove its own pid file. This
option will make start-stop-daemon remove the file referenced with
--pidfile after terminating the process.
- -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 done.
- 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