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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | EXIT STATUS | EXAMPLE | COLOPHON |
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start-stop-daemon(8) dpkg suite start-stop-daemon(8)
start-stop-daemon - start and stop system daemon programs
start-stop-daemon [option...] command
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.
-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.
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) manual
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.
This option might do nothing on some systems, where POSIX
process scheduling is not supported.
-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.
This option might do nothing on some systems, where Linux IO
scheduling is not supported.
-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.
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.
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 /usr/local/var/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 /usr/local/var/run/food.pid --retry 5
Demonstration of a custom schedule for stopping food:
start-stop-daemon --stop --oknodo --user food --name food \
--pidfile /usr/local/var/run/food.pid --retry=TERM/30/KILL/5
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 ⟨git
clone https://git.dpkg.org/git/dpkg/dpkg.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-05-21.) 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
[email protected]
1.22.6-77-g86fe7 2024-03-10 start-stop-daemon(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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