supervise-daemon man page

supervise-daemon ā€” starts a daemon and restarts it if it crashes

Synopsis

supervise-daemon -a, --healthcheck-timer seconds -A, --healthcheck-delay seconds -D, --respawn-delay seconds -d, --chdir path -e, --env var=value -g, --group group -I, --ionice arg -k, --umask value -m, --respawn-max count -N, --nicelevel level -P, --respawn-period seconds -R, --retry arg -r, --chroot chrootpath -u, --user user -1, --stdout logfile -2, --stderr logfile -S, --start daemon [--] [arguments]
supervise-daemon -K, --stop daemon -r, --chroot chrootpath

Description

supervise-daemon provides a consistent method of starting, stopping and restarting daemons. If -K, --stop is not provided, then we assume we are starting the daemon. supervise-daemon only works with daemons which do not fork. Also, it uses its own pid file, so the daemon should not write a pid file, or the pid file passed to supervise-daemon should not be the one the daemon writes.

Here are the options to specify the daemon and how it should start or stop:

-u, --user user[:group]

Start the daemon as the user and update $HOME accordingly or stop daemons owned by the user. You can optionally append a group name here also.

-v, --verbose

Print the action(s) that are taken just before doing them.

The options are as follows: -a, --healthcheck-timer seconds Run the healthcheck() command, possibly followed by the unhealthy() command every time this number of seconds passes. -A, --healthcheck-delay seconds Wait this long before the first health check.

-D, --respawn-delay seconds

wait this number of seconds before restarting a daemon after it crashes. The default is 0.

-d, --chdir path

chdir to this directory before starting the daemon.

-e, --env VAR=VALUE

Set the environment variable VAR to VALUE.

-g, --group group

Start the daemon as in the group.

-I, --ionice class[:data]

Modifies the IO scheduling priority of the daemon. Class can be 0 for none, 1 for real time, 2 for best effort and 3 for idle. Data can be from 0 to 7 inclusive.

-k, --umask mode

Set the umask of the daemon.

-m, --respawn-max count

Sets the maximum number of times a daemon will be respawned during a respawn period. If a daemon dies more than this number of times during a respawn period, supervise-daemon will give up trying to respawn it and exit. The default is 10, and 0 means unlimited.

-N, --nicelevel level

Modifies the scheduling priority of the daemon.

-P, --respawn-period seconds

Sets the length of a respawn period. The default is 10 seconds. See the description of --respawn-max for more information.

-R, --retry timeout | signal/timeout

The retry specification can be either a timeout in seconds or multiple signal/timeout pairs (like SIGTERM/5). If this option is not given, the default is SIGTERM/5.

-r, --chroot path

chroot to this directory before starting the daemon. All other paths, such as the path to the daemon and chdir should be relative to the chroot.

-u, --user user

Start the daemon as the specified user.

-1, --stdout logfile

Redirect the standard output of the process to logfile. Must be an absolute pathname, but relative to the path optionally given with -r, --chroot. The logfile can also be a named pipe.

-2, --stderr logfile

The same thing as -1, --stdout but with the standard error output.

Environment

SSD_NICELEVEL can also set the scheduling priority of the daemon, but the command line option takes precedence.

Note

supervise-daemon uses getopt(3) to parse its options, which allows it to accept the `--' option which will cause it to stop processing options at that point. Any subsequent arguments are passed as arguments to the daemon to start and used when finding a daemon to stop or signal.

Note

If respawn-delay, respawn-max and respawn-period are not set correctly, it is possible to trigger a situation in which the supervisor will infinitely try to respawn a daemon. To avoid this, if you change the values of --respawn-delay, --respawn-max or --respawn-period, always make sure the settings mmake sense. For example, a respawn period of 5 seconds with a respawn max of 10 and a respawn delay of 1 second leads to infinite respawning since there can never be 10 respawns within 5 seconds.

See Also

chdir(2), chroot(2), getopt(3), nice(2),

History

supervise-daemon first appeared in Debian.

This is a complete re-implementation with the process finding code in the OpenRC library (librc, -lrc) so other programs can make use of it.

Authors

William Hubbs <w.d.hubbs@gmail.com>

Referenced By

openrc-run(8), rc-status(8).

April 27, 2016