.\" Copyright (c) 2007-2015 The OpenRC Authors. .\" See the Authors file at the top-level directory of this distribution and .\" https://github.com/OpenRC/openrc/blob/master/AUTHORS .\" .\" This file is part of OpenRC. It is subject to the license terms in .\" the LICENSE file found in the top-level directory of this .\" distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE .\" This file may not be copied, modified, propagated, or distributed .\" except according to the terms contained in the LICENSE file. .\" .Dd April 27, 2016 .Dt SUPERVISE-DAEMON 8 SMM .Os OpenRC .Sh NAME .Nm supervise-daemon .Nd starts a daemon and restarts it if it crashes .Sh SYNOPSIS .Nm servicename .Fl a , -healthcheck-timer .Ar seconds .Fl A , -healthcheck-delay .Ar seconds .Fl D , -respawn-delay .Ar seconds .Fl d , -chdir .Ar path .Fl e , -env .Ar var=value .Fl g , -group .Ar group .Fl I , -ionice .Ar arg .Fl k , -umask .Ar value .Fl m , -respawn-max .Ar count .Fl N , -nicelevel .Ar level .Fl P , -respawn-period .Ar seconds .Fl R , -retry .Ar arg .Fl r , -chroot .Ar chrootpath .Fl u , -user .Ar user .Fl 1 , -stdout .Ar logfile .Fl 2 , -stderr .Ar logfile .Fl S , -start .Ar daemon .Op Fl - .Op Ar arguments .Nm servicename .Fl K , -stop .Ar daemon .Fl r , -chroot .Ar chrootpath .Nm servicename .Fl s , -signal .Ar signal .Fl r , -chroot .Ar chrootpath .Sh DESCRIPTION .Nm provides a consistent method of starting, stopping and restarting daemons. If .Fl K , -stop or .Fl s , -signal is not provided, then we assume we are starting the daemon. .Nm only works with daemons which do not fork. If your daemon has options to tell it not to fork, it should be configured to not fork. .Pp Here are the options to specify the daemon and how it should start or stop: .Bl -tag -width indent .It Fl u , -user Ar user Ns Op : Ns Ar group Start the daemon as the .Ar user and update $HOME accordingly or stop daemons owned by the user. You can optionally append a .Ar group name here also. .It Fl v , -verbose Print the action(s) that are taken just before doing them. .El .Pp The options are as follows: .Bl -tag -width indent .It Fl a , -healthcheck-timer Ar seconds Run the healthcheck() command, possibly followed by the unhealthy() command every time this number of seconds passes. .It Fl A , -healthcheck-delay Ar seconds Wait this long before the first health check. .It Fl D , -respawn-delay Ar seconds Wait this number of seconds before restarting a daemon after it crashes. The default is 0. .It Fl d , -chdir Ar path chdir to this directory before starting the daemon. .It Fl e , -env Ar VAR=VALUE Set the environment variable VAR to VALUE. .It Fl g , -group Ar group Start the daemon as in the group. .It Fl I , -ionice Ar class Ns Op : Ns Ar 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. .It Fl k , -umask Ar mode Set the umask of the daemon. .It Fl m , -respawn-max Ar count Sets the maximum number of times a daemon will be respawned. If a daemon crashes more than this number of times, .Nm will give up and exit. The default is 10 and 0 means unlimited. .Pp If respawn-period is also set, more than respawn-max crashes must occur during respawn-period seconds to cause .Nm to give up and exit. .It Fl N , -nicelevel Ar level Modifies the scheduling priority of the daemon. .It Fl P , -respawn-period Ar seconds Sets the length of a respawn period. See the description of --respawn-max for more information. .It Fl R , -retry Ar timeout | Ar signal Ns / Ns Ar 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. .It Fl r , -chroot Ar 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. .It Fl , -signal Ar signal Instruct a supervisor to signal the process it is supervising. The process to communicate with is determined by the name of the service taken from the RC_SVCNAME environment variable. .It Fl u , -user Ar user Start the daemon as the specified user. .It Fl 1 , -stdout Ar logfile Redirect the standard output of the process to logfile. Must be an absolute pathname, but relative to the path optionally given with .Fl r , -chroot . The logfile can also be a named pipe. .It Fl 2 , -stderr Ar logfile The same thing as .Fl 1 , -stdout but with the standard error output. .El .Sh ENVIRONMENT .Va SSD_NICELEVEL can also set the scheduling priority of the daemon, but the command line option takes precedence. .Sh NOTE .Nm uses .Xr 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. .Sh 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. .Sh NOTE Invoking supervise-daemon requires both the RC_SVCNAME environment variable to be set and the name of the service as the first argument on the command line, so it is best to invoke it inside a service script rather than manually. .Sh SEE ALSO .Xr chdir 2 , .Xr chroot 2 , .Xr getopt 3 , .Xr nice 2 , .Sh HISTORY .Nm first appeared in Debian. .Pp 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. .Sh AUTHORS .An William Hubbs