248 lines
7.0 KiB
Groff
248 lines
7.0 KiB
Groff
.\" Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Berkeley Software Design Inc's name may not be used to endorse or
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.\" promote products derived from this software without specific prior
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.\" written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 14, 2021
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.Dt DAEMON 8
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.Os
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.Sh NAME
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.Nm daemon
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.Nd run detached from the controlling terminal
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.Sh SYNOPSIS
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.Nm
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.Op Fl cfHrS
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.Op Fl p Ar child_pidfile
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.Op Fl P Ar supervisor_pidfile
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.Op Fl t Ar title
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.Op Fl u Ar user
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.Op Fl m Ar output_mask
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.Op Fl o Ar output_file
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.Op Fl s Ar syslog_priority
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.Op Fl T Ar syslog_tag
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.Op Fl l Ar syslog_facility
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.Op Fl R Ar restart_delay_seconds
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.Ar command arguments ...
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.Sh DESCRIPTION
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The
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.Nm
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utility detaches itself from the controlling terminal and
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executes the program specified by its arguments.
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Privileges may be lowered to the specified user.
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The output of the daemonized process may be redirected to syslog and to a
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log file.
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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 c
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Change the current working directory to the root
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.Pq Dq Pa / .
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.It Fl f
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Redirect standard input, standard output and standard error to
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.Pa /dev/null .
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When this option is used together with any of the options related to file
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or syslog output, the standard file descriptors are first redirected to
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.Pa /dev/null ,
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then stdout and/or stderr is redirected to a file or to syslog as
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specified by the other options.
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.It Fl H
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Close
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.Pa output_file
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and re-open it when signal SIGHUP is received, for interoperability with
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.Xr newsyslog 1
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and similar log rotation / archival mechanisms. If
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.Fl o
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is not specified, this flag is ignored.
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.It Fl S
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Enable syslog output.
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This is implicitly applied if other syslog parameters are provided.
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The default values are daemon, notice, and daemon for facility, priority, and
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tag, respectively.
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.It Fl o Ar output_file
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Append output from the daemonized process to
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.Pa output_file .
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If the file does not exist, it is created with permissions 0600.
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When this option is used together with options
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.Fl c
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and
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.Fl H
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the absolute path needs to be provided to ensure
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.Nm
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can re-open the file after a SIGHUP.
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.It Fl m Ar output_mask
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Redirect output from the child process stdout (1), stderr (2), or both (3).
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This value specifies what is sent to syslog and the log file.
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The default is 3.
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.It Fl p Ar child_pidfile
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Write the ID of the created process into the
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.Ar child_pidfile
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using the
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.Xr pidfile 3
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functionality.
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The program is executed in a spawned child process while the
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.Nm
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waits until it terminates to keep the
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.Ar child_pidfile
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locked and removes it after the process exits.
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The
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.Ar child_pidfile
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owner is the user who runs the
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.Nm
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regardless of whether the
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.Fl u
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option is used or not.
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.It Fl P Ar supervisor_pidfile
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Write the ID of the
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.Nm
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process into the
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.Ar supervisor_pidfile
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using the
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.Xr pidfile 3
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functionality.
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The program is executed in a spawned child process while the
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.Nm
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waits until it terminates to keep the
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.Ar supervisor_pidfile
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locked and removes it after the process exits.
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The
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.Ar supervisor_pidfile
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owner is the user who runs the
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.Nm
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regardless of whether the
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.Fl u
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option is used or not.
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.It Fl r
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Supervise and restart the program after a one-second delay if it has
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been terminated.
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.It Fl R Ar restart_delay_seconds
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Supervise and restart the program after the specified delay
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if it has been terminated.
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.It Fl t Ar title
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Set the title for the daemon process.
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The default is the daemonized invocation.
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.It Fl u Ar user
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Login name of the user to execute the program under.
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Requires adequate superuser privileges.
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.It Fl s Ar syslog_priority
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These priorities are accepted: emerg, alert, crit, err, warning,
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notice, info, and debug.
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The default is notice.
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.It Fl l Ar syslog_facility
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These facilities are accepted: auth, authpriv, console, cron, daemon,
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ftp, kern, lpr, mail, news, ntp, security, syslog, user, uucp, and
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local0, ..., local7.
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The default is daemon.
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.It Fl T Ar syslog_tag
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Set the tag which is appended to all syslog messages.
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The default is daemon.
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.El
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.Pp
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If any of the options
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.Fl p ,
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.Fl P ,
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.Fl r ,
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.Fl o ,
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.Fl s ,
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.Fl T ,
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.Fl m ,
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.Fl S ,
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or
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.Fl l
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are specified, the program is executed in a spawned child process.
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The
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.Nm
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waits until it terminates to keep the pid file(s) locked and removes them
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after the process exits or restarts the program.
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In this case if the monitoring
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.Nm
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receives software termination signal (SIGTERM) it forwards it to the
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spawned process.
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Normally it will cause the child to exit, remove the pidfile(s)
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and then terminate.
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.Pp
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If neither file or syslog output are selected, all output is redirected to the
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.Nm
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process and written to stdout.
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The
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.Fl f
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option may be used to suppress the stdout output completely.
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.Pp
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The
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.Fl P
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option is useful combined with the
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.Fl r
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option as
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.Ar supervisor_pidfile
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contains the ID of the supervisor
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not the child.
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This is especially important if you use
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.Fl r
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in an rc script as the
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.Fl p
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option will give you the child's ID to signal when you attempt to
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stop the service, causing
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.Nm
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to restart the child.
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.Sh EXIT STATUS
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The
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.Nm
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utility exits 1 if an error is returned by the
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.Xr daemon 3
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library routine, 2 if
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.Ar child_pidfile
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or
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.Ar supervisor_pidfile
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is requested, but cannot be opened, 3 if process is already running (pidfile
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exists and is locked), 4 if
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.Ar syslog_priority
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is not accepted, 5 if
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.Ar syslog_facility
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is not accepted, 6 if
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.Ar output_mask
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is not within the accepted range, 7 if
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.Ar output_file
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cannot be opened for appending, and otherwise 0.
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.Sh DIAGNOSTICS
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If the command cannot be executed, an error message is printed to
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standard error.
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The exact behavior depends on the logging parameters and the
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.Fl f
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flag.
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.Sh SEE ALSO
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.Xr nohup 1 ,
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.Xr setregid 2 ,
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.Xr setreuid 2 ,
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.Xr daemon 3 ,
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.Xr exec 3 ,
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.Xr pidfile 3 ,
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.Xr termios 4 ,
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.Xr tty 4
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Fx 4.7 .
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