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RC.SUBR(8)		  BSD 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
     set_rcvar [base]
     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 and it is intended
     that they remain synced between the two projects.	With that in mind
     there are several variable definitions that can help in this regard.
     They are:

     OSTYPE
	   Its value will be either "FreeBSD" or "NetBSD", depending on which
	   OS it is running on.

     SYSCTL
	   The path to the sysctl(8) command.

     SYSCTL_N
	   The path and argument list to display only the sysctl(8) values
	   instead of a name=value pair.

     SYSCTL_W
	   The path and argument to write or modify sysctl(8) values.

     The rc.subr functions are accessed by sourcing /etc/rc.subr into the cur‐
     rent 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 insensi‐
	   tive.  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]”.

     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).

		 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 per‐
			forms all the other prerequisite tests.

	   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 description
			   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.

     set_rcvar [base]
	   Set the variable name required to start a service.  In FreeBSD a
	   daemon is usually controlled by an rc.conf(5) variable consisting
	   of a daemon's name postfixed by the string “_enable”.  This is not
	   the case in NetBSD.	When the following line is included in a
	   script:

		 rcvar=`set_rcvar`

	   this function will use the value of the $name variable, which
	   should be defined by the calling script, to construct the appropri‐
	   ate rc.conf(5) knob.	 If the base argument is set it will use base
	   instead of $name.

     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.

BSD				 May 18, 2007				   BSD
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