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


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

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)

       -q, --quiet
              Do not print informational messages; only display error

       -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.

              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:

                     The program is ready to give service, so we can exit

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

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

              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.

              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

       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

              start-stop-daemon --start --oknodo --user food --name food \
                   --pidfile /run/ --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/ --retry 5

       Demonstration of a custom schedule for stopping food:

              start-stop-daemon --stop --oknodo --user food --name food \
                   --pidfile /run/ --retry=TERM/30/KILL/5

COLOPHON         top

       This page is part of the dpkg (Debian Package Manager) project.
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       ⟨⟩.  This page
       was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-07-14.  (At
       that time, the date of the most recent commit that was found in the
       repository was 2020-07-08.)  If you discover any rendering problems
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       of the original manual page), send a mail to

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