bionic (8) start-stop-daemon.8.gz
NAME
start-stop-daemon - start and stop system daemon programs
SYNOPSIS
start-stop-daemon [option...] command
DESCRIPTION
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.
COMMANDS
-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 terminated.
-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).
-H, --help
Show usage information and exit.
-V, --version
Show the program version and exit.
OPTIONS
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.
--ppid ppid
Check for a process with the specified parent pid ppid (since version 1.17.7). 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 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 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.
-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 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 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 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 (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 it.
-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 and real-time.
-k, --umask mask
This sets the umask of the process before starting it (since version 1.13.22).
-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.
--remove-pidfile
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.
-v, --verbose
Print verbose informational messages.
EXIT STATUS
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 returned:
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.
EXAMPLE
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