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NetBSD 6.1.5 - man page for rc.subr (netbsd section 8)

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]

     collapse_backslash_newline

     err exitval message

     load_rc_config command

     load_rc_config_var command var

     mount_critical_filesystems type

     no_rc_postprocess command [arguments]

     print_rc_metadata string

     print_rc_normal [-n] string

     rc_usage command [...]

     reverse_list item [...]

     run_rc_command argument [parameters]

     run_rc_script file argument

     stop_boot

     twiddle

     wait_for_pids [pid [...]]

     warn message

     yesno_to_truefalse var

DESCRIPTION
     rc.subr contains commonly used shell script functions which are used by various scripts such
     as rc(8), and the periodic system services which are controlled by daily.conf(5),
     monthly.conf(5), security.conf(5), and weekly.conf(5).

     The rc.subr functions 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) variable backup_uses_rcs
	   is 'YES', use rcs(1) to archive the previous version of current, otherwise save the
	   previous version of current as backup.

	   action may be one of the following:

	   add	   file is now being backed up by or possibly re-entered into this backup mecha-
		   nism.  current is created, and if necessary, 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 that the warning message shown by this function when var is not set references a
	   manual page where the user can find more information.  Its name is picked up from the
	   rcvar_manpage variable.

     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.

     collapse_backslash_newline
	   Copy input to output, collapsing <backslash><newline> to nothing, but leaving other
	   backslashes alone.

     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 message consists of the script name (from
	   $0), followed by ``: ERROR: '', and then message.

     load_rc_config command
	   Source in the rc.conf(5) configuration files for command.  First, /etc/rc.conf is
	   sourced if it has not yet been read in.  Then, /etc/rc.conf.d/command is sourced if it
	   is an existing file.  The latter may also contain other variable assignments to over-
	   ride run_rc_command arguments defined by the calling script, to provide an easy mecha-
	   nism 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 command var
	   Read the rc.conf(5) variable var for command 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.

     no_rc_postprocess command [arguments]
	   Execute the specified command with the specified arguments, in such a way that its
	   output bypasses the post-processor that rc(8) uses for most commands.  This implies
	   that the output will not appear in the /var/run/rc.log file, and will appear on the
	   console regardless of the value of rc_silent.  This is expected to be useful for
	   interactive commands, and this mechanism is automatically used by run_rc_command when
	   a script contains the rcorder(8) keyword ``interactive''.

	   If invoked from a context that does not appear to be under the control of rc(8), then
	   the command is executed without special treatment.

     print_rc_metadata string
	   Print the specified string in such a way that it should be handled as meta-data by the
	   rc(8) post-processor.  If invoked from a context that does not appear to be under the
	   control of rc(8), then the string is discarded.

	   Any rc.d(8) script may invoke this function with an argument that begins with
	   ``note:'', followed by one line of arbitrary text; the text will be logged by rc(8)
	   but will not be displayed on the console.

	   The use of arguments that do not begin with ``note:'' is reserved for internal use by
	   rc(8) and rc.subr.

     print_rc_normal [-n] string
	   Print the specified string in such a way that it should be handled as normal output by
	   the rc(8) post-processor.  If invoked from a context that does not appear to be under
	   the control of rc(8), then the string is printed to standard output.

	   If the -n flag is specified, then the string is printed without a newline.

	   Intended use cases include:

	   o   An rc.d script can use ``print_rc_normal -n'' to print a partial line in such a
	       way that it appears immediately instead of being buffered by rc(8)'s post-proces-
	       sor.

	   o   An rc.d script that is run via the no_rc_postprocess function (so most of its out-
	       put is invisible to rc(8)'s post-processor) can use print_rc_normal to force some
	       of its output to be seen by the post-processor.

     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 [parameter ...]
	   Run the argument method for the current rc.d(8) script, based on the settings of vari-
	   ous shell variables.  run_rc_command is extremely flexible, and allows fully func-
	   tional rc.d(8) scripts to be implemented in a small amount of shell code.  The
	   optional set of parameters is passed verbatim to the command, but not to its pre/post
	   hooks.

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

		 start	  Start the service.  This should check that the service is to be started
			  as specified by rc.conf(5).  Also checks if the service is already run-
			  ning and refuses to start if it is.  This latter check is not performed
			  by standard NetBSD 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's 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 control 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.

	   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.

		 rcvar_manpage
			   The manual page containing information about rcvar.	It will be part
			   of the warning message shown when rcvar is undefined.  Defaults to
			   rc.conf(5).

		 command   Full path to the command.  Not required if argument_cmd is defined for
			   each supported keyword.

		 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 running 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 com-
			   mand.  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
			   default start method.

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

		 required_vars
			   Perform checkyesno on each of the list variables before running the
			   default 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}_env
			   List of additional or modified environment variables to set when
			   starting command.

		 ${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}_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 succeeds, 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 doesn't
			   run wait_for_pids.

		 restart   Runs the stop method, then the start method.

		 status    Show the PID of command, or some other script specific status opera-
			   tion.

		 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 environment 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.

	   5.	If file contains the rcorder(8) keyword ``interactive'', then the command is exe-
		cuted using no_rc_postprocess.

     stop_boot
	   Prevent booting to multiuser mode.  If the autoboot variable is 'yes', then a SIGTERM
	   signal is sent to the parent process (which is assumed to be rc(8)).  Otherwise, the
	   shell exits with status 1.

     twiddle
	   Display one of the characters '/, -, \, |', followed by a backspace.  Repeated calls
	   to this function will create the appearance of a spinning symbol, as a different char-
	   acter is displayed on each call.  Output is to /dev/tty, so this function may be use-
	   ful even inside a script whose output has been redirected.

     wait_for_pids [pid [...]]
	   Wait until all of the provided pids don't exist any more, printing the list of out-
	   standing 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.

     yesno_to_truefalse var
	   Change the value of the specified variable from any of the forms acceptable to the
	   checkyesno function, to ``true'' or ``false''.

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

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

HISTORY
     rc.subr appeared in NetBSD 1.3.  The rc.d(8) support functions appeared in NetBSD 1.5.  Sup-
     port for the rc(8) post-processor appeared in NetBSD 6.0.

BSD					 August 11, 2011				      BSD


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