Updated: 2021/Apr/14

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

     rc.subr - functions used by system shell scripts

     . /etc/rc.subr

     backup_file action file current backup

     basename file [suffix]

     checkyesno var

     check_pidfile pidfile procname [interpreter]

     check_process procname [interpreter]


     dirname file

     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



     wait_for_pids [pid [...]]

     warn message

     yesno_to_truefalse var

     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

     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 mechanism.  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

           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.

     basename file [suffix]
           Just like basename(1), except implemented using shell built-in
           commands, and usable before the /usr/bin direcory is available.

     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

           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

     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

           Copy input to output, collapsing <backslash><newline> to nothing,
           but leaving other backslashes alone.  dirname file Just like
           dirname(1), except implemented using shell built-in commands, and
           usable before the /usr/bin direcory is available.

     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 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

     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

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

     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

           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

           Intended use cases include:

              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-processor.

              An rc.d script that is run via the no_rc_postprocess function
               (so most of its output 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 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.  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 running 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

                 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

           argument may have one of the following prefixes which alters its

                 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.

                           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.

                           Optional arguments and/or shell directives for

                           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/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.

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

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

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

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

                           Directory to chroot(8) to before running command.
                           Only supported after /usr is mounted.

                           List of additional or modified environment
                           variables to set when starting command.

                           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.

                           nice(1) level to run command as.  Only supported
                           after /usr is mounted.

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

                           Group to run the chrooted command as.

                           Comma separated list of supplementary groups to run
                           the chrooted command with.

                           Shell commands which override the default method
                           for argument.

                           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

                           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.

                           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 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
                           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.

           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

           5.   If file contains the rcorder(8) keyword "interactive", then
                the command is executed using no_rc_postprocess.

           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.

           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 character is
           displayed on each call.  Output is to /dev/tty, so this function
           may be useful even inside a script whose output has been

     wait_for_pids [pid [...]]
           Wait until all of the provided pids don't 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.

     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".

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

     rc.conf(5), rc(8)

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

NetBSD 9.99                    December 17, 2012                   NetBSD 9.99