start-stop-daemon
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 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 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-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
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
1.19.7 2022-05-25 start-stop-daemon(8)
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