phpman > man > start-stop-daemon(8)

start-stop-daemon(8)                         dpkg suite                         start-stop-daemon(8)



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 pidfile
           Check whether a process has created the file pidfile.

           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 pidfile.

           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 checks.

       -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
           Change directory and chroot to root before starting the process. Please note that the
           pidfile is also written after the chroot.

       -d, --chdir path
           Change directory 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 change
           directory 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.

       --notify-await
           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
           protocol, as specified in the sd_notify(3) man page.  The following variables are
           supported:

           READY=1
               The program is ready to give service, so we can exit safely.

           EXTEND_TIMEOUT_USEC=number
               The program requests to extend the timeout by number microseconds.  This will reset
               the current timeout to the specified value.

           ERRNO=number
               The program is exiting with an error.  Do the same and print the user-friendly string
               for the errno value.

       --notify-timeout timeout
           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.

       -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.

       -O, --output pathname
           Redirect stdout and stderr to pathname when forcing the daemon into the background (since
           version 1.20.6).  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



1.21.1                                       2025-09-09                         start-stop-daemon(8)