172 lines
5.1 KiB
Groff
172 lines
5.1 KiB
Groff
.\" Copyright (c) 2007-2015 The OpenRC Authors.
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.\" See the Authors file at the top-level directory of this distribution and
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.\" https://github.com/OpenRC/openrc/blob/master/AUTHORS
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.\"
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.\" This file is part of OpenRC. It is subject to the license terms in
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.\" the LICENSE file found in the top-level directory of this
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.\" distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
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.\" This file may not be copied, modified, propagated, or distributed
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.\" except according to the terms contained in the LICENSE file.
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.\"
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.Dd April 27, 2016
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.Dt supervise-DAEMON 8 SMM
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.Os OpenRC
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.Sh NAME
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.Nm supervise-daemon
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.Nd starts a daemon and restarts it if it crashes
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.Sh SYNOPSIS
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.Nm
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.Fl D , -respawn-delay
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.Ar seconds
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.Fl d , -chdir
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.Ar path
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.Fl e , -env
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.Ar var=value
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.Fl g , -group
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.Ar group
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.Fl I , -ionice
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.Ar arg
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.Fl k , -umask
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.Ar value
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.Fl m , -respawn-max
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.Ar count
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.Fl N , -nicelevel
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.Ar level
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.Fl p , -pidfile
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.Ar pidfile
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.Fl P , -respawn-period
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.Ar seconds
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.Fl r , -chroot
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.Ar chrootpath
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.Fl u , -user
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.Ar user
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.Fl 1 , -stdout
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.Ar logfile
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.Fl 2 , -stderr
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.Ar logfile
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.Fl S , -start
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.Ar daemon
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.Op Fl -
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.Op Ar arguments
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.Nm
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.Fl K , -stop
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.Ar daemon
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.Fl p , -pidfile
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.Ar pidfile
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.Fl r , -chroot
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.Ar chrootpath
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.Sh DESCRIPTION
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.Nm
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provides a consistent method of starting, stopping and restarting
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daemons. If
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.Fl K , -stop
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is not provided, then we assume we are starting the daemon.
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.Nm
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only works with daemons which do not fork. Also, it uses its own pid
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file, so the daemon should not write a pid file, or the pid file passed
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to
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.Nm
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should not be the one the daemon writes.
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.Pp
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Here are the options to specify the daemon and how it should start or stop:
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.Bl -tag -width indent
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.It Fl p , -pidfile Ar pidfile
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When starting, we write a
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.Ar pidfile
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so we know which supervisor to stop. When stopping we only stop the pid(s)
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listed in the
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.Ar pidfile .
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.It Fl u , -user Ar user Ns Op : Ns Ar group
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Start the daemon as the
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.Ar user
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and update $HOME accordingly or stop daemons
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owned by the user. You can optionally append a
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.Ar group
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name here also.
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.It Fl v , -verbose
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Print the action(s) that are taken just before doing them.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl D , -respawn-delay Ar seconds
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wait this number of seconds before restarting a daemon after it crashes.
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The default is 0.
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.It Fl d , -chdir Ar path
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chdir to this directory before starting the daemon.
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.It Fl e , -env Ar VAR=VALUE
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Set the environment variable VAR to VALUE.
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.It Fl g , -group Ar group
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Start the daemon as in the group.
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.It Fl I , -ionice Ar class Ns Op : Ns Ar data
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Modifies the IO scheduling priority of the daemon.
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Class can be 0 for none, 1 for real time, 2 for best effort and 3 for idle.
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Data can be from 0 to 7 inclusive.
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.It Fl k , -umask Ar mode
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Set the umask of the daemon.
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.It Fl m , -respawn-max Ar count
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Sets the maximum number of times a daemon will be respawned during a
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respawn period. If a daemon dies more than this number of times during a
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respawn period,
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.Nm
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will give up trying to respawn it and exit. The default is 10, and 0
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means unlimited.
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.It Fl N , -nicelevel Ar level
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Modifies the scheduling priority of the daemon.
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.It Fl P , -respawn-period Ar seconds
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Sets the length of a respawn period. The default is 10 seconds. See the
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description of --respawn-max for more information.
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.It Fl r , -chroot Ar path
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chroot to this directory before starting the daemon. All other paths, such
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as the path to the daemon, chdir and pidfile, should be relative to the chroot.
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.It Fl u , -user Ar user
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Start the daemon as the specified user.
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.It Fl 1 , -stdout Ar logfile
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Redirect the standard output of the process to logfile.
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Must be an absolute pathname, but relative to the path optionally given with
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.Fl r , -chroot .
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The logfile can also be a named pipe.
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.It Fl 2 , -stderr Ar logfile
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The same thing as
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.Fl 1 , -stdout
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but with the standard error output.
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.El
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.El
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.Sh ENVIRONMENT
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.Va SSD_NICELEVEL
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can also set the scheduling priority of the daemon, but the command line
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option takes precedence.
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.Sh NOTE
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.Nm
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uses
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.Xr getopt 3
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to parse its options, which allows it to accept the `--' option which will
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cause it to stop processing options at that point. Any subsequent arguments
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are passed as arguments to the daemon to start and used when finding a daemon
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to stop or signal.
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.Sh NOTE
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If respawn-delay, respawn-max and respawn-period are not set correctly,
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it is possible to trigger a situation in which the supervisor will
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infinitely try to respawn a daemon. To avoid this, if you change the
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values of --respawn-delay, --respawn-max or --respawn-period, always
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make sure the settings mmake sense. For example, a respawn period of 5
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seconds with a respawn max of 10 and a respawn delay of 1 second leads
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to infinite respawning since there can never be 10 respawns within 5
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seconds.
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.Sh SEE ALSO
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.Xr chdir 2 ,
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.Xr chroot 2 ,
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.Xr getopt 3 ,
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.Xr nice 2 ,
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.Xr rc_find_pids 3
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.Sh BUGS
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.Nm
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cannot stop an interpreted daemon that no longer exists without a pidfile.
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.Sh HISTORY
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.Nm
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first appeared in Debian.
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.Pp
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This is a complete re-implementation with the process finding code in the
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OpenRC library (librc, -lrc) so other programs can make use of it.
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.Sh AUTHORS
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.An William Hubbs <w.d.hubbs@gmail.com>
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