start-stop-daemon(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | EXIT STATUS | EXAMPLE | COLOPHON

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

NAME         top

       start-stop-daemon - start and stop system daemon programs

SYNOPSIS         top

       start-stop-daemon [option...] command

DESCRIPTION         top

       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         top

       -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         top

   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.

              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
              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.

       --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 procotol, 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-timeouttimeout
              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.

       -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         top

       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         top

       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

COLOPHON         top

       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
       ⟨http://bugs.debian.org/cgi-bin/pkgreport.cgi?src=dpkg⟩.  This
       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
       man-pages@man7.org

1.19.6-2-g6e42d5               2019-03-25           start-stop-daemon(8)