Provided by: dpkg_1.19.7ubuntu3.2_amd64 
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