RC.SUBR(8)

NAME
rc.subr - functions used by system shell scripts

SYNOPSIS

. /etc/rc.subr

backup_file action file current backup

basename file [suffix]

checkyesno var

check_pidfile pidfile procname [interpreter]

check_process procname [interpreter]

collapse_backslash_newline

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

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 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 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.
    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 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. 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 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:

    •   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 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 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 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 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. 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 executed 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 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 redirected.

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”.

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. Support for the rc(8) post-processor appeared in NetBSD 6.0.