start-stop-daemon
Section: dpkg suite (8)
Updated: 1970-01-01
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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