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RC.SUBR(8)		FreeBSD	System Manager's Manual		    RC.SUBR(8)

NAME
     rc.subr --	functions used by system shell scripts

SYNOPSIS
     . /etc/rc.subr

     backup_file action	file current backup
     checkyesno	var
     check_pidfile pidfile procname [interpreter]
     check_process procname [interpreter]
     debug message
     err exitval message
     force_depend name
     info message
     load_kld [-e regex] [-m module] file
     load_rc_config name
     load_rc_config_var	name var
     mount_critical_filesystems	type
     rc_usage command ...
     reverse_list item ...
     run_rc_command argument
     run_rc_script file	argument
     wait_for_pids [pid	...]
     warn message

DESCRIPTION
     The rc.subr script	contains commonly used shell script functions and
     variable definitions which	are used by various scripts such as rc(8).
     Scripts required by ports in /usr/local/etc/rc.d will also	eventually be
     rewritten to make use of it.

     The rc.subr functions were	mostly imported	from NetBSD.

     They are accessed by sourcing /etc/rc.subr	into the current shell.

     The following shell functions are available:

     backup_file action	file current backup
	   Make	a backup copy of file into current.  If	the rc.conf(5) vari-
	   able	backup_uses_rcs	is ``YES'', use	rcs(1) to archive the previous
	   version of current, otherwise save the previous version of current
	   as backup.

	   The action argument may be one of the following:

	   add	   file	is now being backed up by or possibly re-entered into
		   this	backup mechanism.  current is created, and if neces-
		   sary, the rcs(1) files are created as well.

	   update  file	has changed and	needs to be backed up.	If current
		   exists, it is copied	to backup or checked into rcs(1) (if
		   the repository file is old),	and then file is copied	to
		   current.

	   remove  file	is no longer being tracked by this backup mechanism.
		   If rcs(1) is	being used, an empty file is checked in	and
		   current is removed, otherwise current is moved to backup.

     checkyesno	var
	   Return 0 if var is defined to ``YES'', ``TRUE'', ``ON'', or `1'.
	   Return 1 if var is defined to ``NO'', ``FALSE'', ``OFF'', or	`0'.
	   Otherwise, warn that	var is not set correctly.  The values are case
	   insensitive.	 Note: var should be a variable	name, not its value;
	   checkyesno will expand the variable by itself.

     check_pidfile pidfile procname [interpreter]
	   Parses the first word of the	first line of pidfile for a PID, and
	   ensures that	the process with that PID is running and its first
	   argument matches procname.  Prints the matching PID if successful,
	   otherwise nothing.  If interpreter is provided, parse the first
	   line	of procname, ensure that the line is of	the form:

		 #! interpreter	[...]

	   and use interpreter with its	optional arguments and procname
	   appended as the process string to search for.

     check_process procname [interpreter]
	   Prints the PIDs of any processes that are running with a first
	   argument that matches procname.  interpreter	is handled as per
	   check_pidfile.

     debug message
	   Display a debugging message to stderr, log it to the	system log
	   using logger(1), and	return to the caller.  The error message con-
	   sists of the	script name (from $0), followed	by ``: DEBUG: '', and
	   then	message.  This function	is intended to be used by developers
	   as an aid to	debugging scripts.  It can be turned on	or off by the
	   rc.conf(5) variable rc_debug.

     err exitval message
	   Display an error message to stderr, log it to the system log	using
	   logger(1), and exit with an exit value of exitval.  The error mes-
	   sage	consists of the	script name (from $0), followed	by ``: ERROR:
	   '', and then	message.

     force_depend name
	   Output an advisory message and force	the name service to start.
	   The name argument is	the basename(1)	component of the path to the
	   script, usually /etc/rc.d/name.  If the script fails	for any	reason
	   it will output a warning and	return with a return value of 1.  If
	   it was successful it	will return 0.

     info message
	   Display an informational message to stdout, and log it to the sys-
	   tem log using logger(1).  The message consists of the script	name
	   (from $0), followed by ``: INFO: '',	and then message.  The display
	   of this informational output	can be turned on or off	by the
	   rc.conf(5) variable rc_info.

     load_kld [-e regex] [-m module] file
	   Load	file as	a kernel module	unless it is already loaded.  For the
	   purpose of checking the module status, either the exact module name
	   can be specified using -m, or an egrep(1) regular expression	match-
	   ing the module name can be supplied via -e.	By default, the	module
	   is assumed to have the same name as file, which is not always the
	   case.

     load_rc_config name
	   Source in the configuration files for name.	First, /etc/rc.conf is
	   sourced if it has not yet been read in.  Then, /etc/rc.conf.d/name
	   is sourced if it is an existing file.  The latter may also contain
	   other variable assignments to override run_rc_command arguments
	   defined by the calling script, to provide an	easy mechanism for an
	   administrator to override the behaviour of a	given rc.d(8) script
	   without requiring the editing of that script.

     load_rc_config_var	name var
	   Read	the rc.conf(5) variable	var for	name and set in	the current
	   shell, using	load_rc_config in a sub-shell to prevent unwanted side
	   effects from	other variable assignments.

     mount_critical_filesystems	type
	   Go through a	list of	critical file systems, as found	in the
	   rc.conf(5) variable critical_filesystems_type, mounting each	one
	   that	is not currently mounted.

     rc_usage command ...
	   Print a usage message for $0, with commands being the list of valid
	   arguments prefixed by ``[fast|force|one|quiet]''.

     reverse_list item ...
	   Print the list of items in reverse order.

     run_rc_command argument
	   Run the argument method for the current rc.d(8) script, based on
	   the settings	of various shell variables.  run_rc_command is
	   extremely flexible, and allows fully	functional rc.d(8) scripts to
	   be implemented in a small amount of shell code.

	   argument is searched	for in the list	of supported commands, which
	   may be one of:

		 start	  Start	the service.  This should check	that the ser-
			  vice is to be	started	as specified by	rc.conf(5).
			  Also checks if the service is	already	running	and
			  refuses to start if it is.  This latter check	is not
			  performed by standard	FreeBSD	scripts	if the system
			  is starting directly to multi-user mode, to speed up
			  the boot process.

		 stop	  If the service is to be started as specified by
			  rc.conf(5), stop the service.	 This should check
			  that the service is running and complain if it is
			  not.

		 restart  Perform a stop then a	start.	Defaults to displaying
			  the process ID of the	program	(if running).

		 enabled  Return 0 if the service is enabled and 1 if it is
			  not.	This command does not print anything.

		 rcvar	  Display which	rc.conf(5) variables are used to con-
			  trol the startup of the service (if any).

	   If pidfile or procname is set, also support:

		 poll	  Wait for the command to exit.

		 status	  Show the status of the process.

	   Other supported commands are	listed in the optional variable
	   extra_commands.

	   argument may	have one of the	following prefixes which alters	its
	   operation:

		 fast	Skip the check for an existing running process,	and
			sets rc_fast=YES.

		 force	Skip the checks	for rcvar being	set to ``YES'',	and
			sets rc_force=YES.  This ignores argument_precmd
			returning non-zero, and	ignores	any of the required_*
			tests failing, and always returns a zero exit status.

		 one	Skip the checks	for rcvar being	set to ``YES'',	but
			performs all the other prerequisite tests.

		 quiet	Inhibits some verbose diagnostics.  Currently, this
			includes messages "Starting ${name}" (as checked by
			check_startmsgs	inside rc.subr)	and errors about usage
			of services that are not enabled in rc.conf(5).	 This
			prefix also sets rc_quiet=YES.	Please,	note: rc_quiet
			is not intended	to completely mask all debug and warn-
			ing messages, but only certain small classes of	them.

	   run_rc_command uses the following shell variables to	control	its
	   behaviour.  Unless otherwise	stated,	these are optional.

		 name	   The name of this script.  This is not optional.

		 rcvar	   The value of	rcvar is checked with checkyesno to
			   determine if	this method should be run.

		 command   Full	path to	the command.  Not required if
			   argument_cmd	is defined for each supported keyword.
			   Can be overridden by	${name}_program.

		 command_args
			   Optional arguments and/or shell directives for
			   command.

		 command_interpreter
			   command is started with:

				 #! command_interpreter	[...]

			   which results in its	ps(1) command being:

				 command_interpreter [...] command

			   so use that string to find the PID(s) of the	run-
			   ning	command	rather than command.

		 extra_commands
			   Extra commands/keywords/arguments supported.

		 pidfile   Path	to PID file.  Used to determine	the PID(s) of
			   the running command.	 If pidfile is set, use:

				 check_pidfile $pidfile	$procname

			   to find the PID.  Otherwise,	if command is set,
			   use:

				 check_process $procname

			   to find the PID.

		 procname  Process name	to check for.  Defaults	to the value
			   of command.

		 required_dirs
			   Check for the existence of the listed directories
			   before running the start method.

		 required_files
			   Check for the readability of	the listed files
			   before running the start method.

		 required_modules
			   Ensure that the listed kernel modules are loaded
			   before running the start method.  This is done
			   after invoking the commands from start_precmd so
			   that	the missing modules are	not loaded in vain if
			   the preliminary commands indicate a error condi-
			   tion.  A word in the	list can have an optional
			   ``:modname''	or ``~pattern''	suffix.	 The modname
			   or pattern parameter	is passed to load_kld through
			   a -m	or -e option, respectively.  See the descrip-
			   tion	of load_kld in this document for details.

		 required_vars
			   Perform checkyesno on each of the list variables
			   before running the start method.

		 ${name}_chdir
			   Directory to	cd to before running command, if
			   ${name}_chroot is not provided.

		 ${name}_chroot
			   Directory to	chroot(8) to before running command.
			   Only	supported after	/usr is	mounted.

		 ${name}_flags
			   Arguments to	call command with.  This is usually
			   set in rc.conf(5), and not in the rc.d(8) script.
			   The environment variable `flags' can	be used	to
			   override this.

		 ${name}_nice
			   nice(1) level to run	command	as.  Only supported
			   after /usr is mounted.

		 ${name}_program
			   Full	path to	the command.  Overrides	command	if
			   both	are set, but has no effect if command is
			   unset.  As a	rule, command should be	set in the
			   script while	${name}_program	should be set in
			   rc.conf(5).

		 ${name}_user
			   User	to run command as, using chroot(8) if
			   ${name}_chroot is set, otherwise uses su(1).	 Only
			   supported after /usr	is mounted.

		 ${name}_group
			   Group to run	the chrooted command as.

		 ${name}_groups
			   Comma separated list	of supplementary groups	to run
			   the chrooted	command	with.

		 argument_cmd
			   Shell commands which	override the default method
			   for argument.

		 argument_precmd
			   Shell commands to run just before running
			   argument_cmd	or the default method for argument.
			   If this returns a non-zero exit code, the main
			   method is not performed.  If	the default method is
			   being executed, this	check is performed after the
			   required_* checks and process (non-)existence
			   checks.

		 argument_postcmd
			   Shell commands to run if running argument_cmd or
			   the default method for argument returned a zero
			   exit	code.

		 sig_stop  Signal to send the processes	to stop	in the default
			   stop	method.	 Defaults to SIGTERM.

		 sig_reload
			   Signal to send the processes	to reload in the
			   default reload method.  Defaults to SIGHUP.

	   For a given method argument,	if argument_cmd	is not defined,	then a
	   default method is provided by run_rc_command:

		 Argument  Default method

		 start	   If command is not running and checkyesno rcvar suc-
			   ceeds, start	command.

		 stop	   Determine the PIDs of command with check_pidfile or
			   check_process (as appropriate), kill	sig_stop those
			   PIDs, and run wait_for_pids on those	PIDs.

		 reload	   Similar to stop, except that	it uses	sig_reload
			   instead, and	does not run wait_for_pids.  Another
			   difference from stop	is that	reload is not provided
			   by default.	It can be enabled via extra_commands
			   if appropriate:

				 extra_commands=reload

		 restart   Runs	the stop method, then the start	method.

		 status	   Show	the PID	of command, or some other script spe-
			   cific status	operation.

		 poll	   Wait	for command to exit.

		 rcvar	   Display which rc.conf(5) variable is	used (if any).
			   This	method always works, even if the appropriate
			   rc.conf(5) variable is set to ``NO''.

	   The following variables are available to the	methods	(such as
	   argument_cmd) as well as after run_rc_command has completed:

		 rc_arg	   Argument provided to	run_rc_command,	after fast and
			   force processing has	been performed.

		 rc_flags  Flags to start the default command with.  Defaults
			   to ${name}_flags, unless overridden by the environ-
			   ment	variable `flags'.  This	variable may be
			   changed by the argument_precmd method.

		 rc_pid	   PID of command (if appropriate).

		 rc_fast   Not empty if	``fast'' prefix	was used.

		 rc_force  Not empty if	``force'' prefix was used.

     run_rc_script file	argument
	   Start the script file with an argument of argument, and handle the
	   return value	from the script.

	   Various shell variables are unset before file is started:

		 name, command,	command_args, command_interpreter,
		 extra_commands, pidfile, rcvar, required_dirs,
		 required_files, required_vars,	argument_cmd, argument_precmd.
		 argument_postcmd.

	   The startup behaviour of file depends upon the following checks:

	   1.	If file	ends in	.sh, it	is sourced into	the current shell.

	   2.	If file	appears	to be a	backup or scratch file (e.g., with a
		suffix of ~, #,	.OLD, or .orig), ignore	it.

	   3.	If file	is not executable, ignore it.

	   4.	If the rc.conf(5) variable rc_fast_and_loose is	empty, source
		file in	a sub shell, otherwise source file into	the current
		shell.

     stop_boot [always]
	   Prevent booting to multiuser	mode.  If the autoboot variable	is set
	   to `yes', or	checkyesno always indicates a truth value, then	a
	   SIGTERM signal is sent to the parent	process, which is assumed to
	   be rc(8).  Otherwise, the shell exits with a	non-zero status.

     wait_for_pids [pid	...]
	   Wait	until all of the provided pids do not exist any	more, printing
	   the list of outstanding pids	every two seconds.

     warn message
	   Display a warning message to	stderr and log it to the system	log
	   using logger(1).  The warning message consists of the script	name
	   (from $0), followed by ``: WARNING: '', and then message.

FILES
     /etc/rc.subr  The rc.subr file resides in /etc.

SEE ALSO
     rc.conf(5), rc(8)

HISTORY
     The rc.subr script	appeared in NetBSD 1.3.	 The rc.d(8) support functions
     appeared in NetBSD	1.5.  The rc.subr script first appeared	in
     FreeBSD 5.0.

FreeBSD	10.1		      September	23, 2012		  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | HISTORY

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