RC.SUBR(8)

RC.SUBR(8) | 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
- `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.

December 17, 2012 | NetBSD 11.0