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

rc.subr — functions used by system shell scripts

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.

They are accessed by sourcing /etc/rc.subr into the current shell.

The following shell functions are available:

action file current backup
Make a backup copy of file into current. Save the previous version of current as backup.

The action argument may be one of the following:

file is now being backed up by or possibly re-entered into this backup mechanism. current is created.
file has changed and needs to be backed up. If current exists, it is copied to backup and then file is copied to current.
file is no longer being tracked by this backup mechanism. current is moved to backup.
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: var should be a variable name, not its value; checkyesno will expand the variable by itself.
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.

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.
tag ...
Enable tracing if not already enabled, and any tag is found in DEBUG_SH (a comma separated list of tags).

Record the tag that caused it to be enabled in DEBUG_ON, set DEBUG_DO empty and DEBUG_SKIP to ‘:’.

See debug.sh(8) for more details.

tag ...
Disable tracing if enabled and any tag matches DEBUG_ON, which means it was the reason tracing was enabled.

Set DEBUG_DO to ‘:’, and DEBUG_ON, DEBUG_SKIP empty.

message
Display a debugging message to stderr, log it to the system log using logger(1), and return to the caller. The error message consists 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.
file ...
For reading in unverified files.

Ensure shell verify option is off. This option is only meaningful when mac_veriexec(4) is active.

Read each file if it exists.

Restore previous state of the verify option.

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.
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 located at /etc/rc.d (scripts stored in other locations such as /usr/local/etc/rc.d cannot be controlled with force_depend currently). 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.
file
If veriexec(8) does not exist, or mac_veriexec(4) is not active, just return success. Otherwise use veriexec(8) to check if file is verified. If not verified the return code will be 80 (EAUTH).
message
Display an informational message to stdout, and log it to the system 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.
[-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 matching 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.
[flag] [service]
Source in the configuration file(s) for service. If no service is specified, only the global configuration file(s) will be loaded. First, /etc/rc.conf is sourced if it has not yet been read in. Then, /etc/rc.conf.d/service 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.

The function named by load_rc_config_reader (default is dot) is used to read configuration unless flag is:

use sdot to read configuration, because we want verified configuration or to use safe_dot to read an unverified configuration.
use vdot to read in configuration only if it is verified.

DebugOn will be called with tags derived from name to enable tracing if any appear in DEBUG_SH.

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.
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.
message
Output message with a timestamp, which is both human readable and easily parsed for post processing, using: 
date "+@ %s [%Y-%m-%d %H:%M:%S %Z] $*"
level message
If the file /etc/rc.conf.d/rc_trace exists and is not empty attempt to set RC_LEVEL based on its content. If the file is empty or does not contain a value for RC_LEVEL, set it to 0.

If level is greater than or equal to RC_LEVEL pass message to rc_log.

command ...
Print a usage message for $0, with commands being the list of valid arguments prefixed by “[fast|force|one|quiet]”.
item ...
Print the list of items in reverse order.
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 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 FreeBSD scripts if the system is starting directly to multi-user mode, to speed up the boot process.
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.
Perform a stop then a start. Defaults to displaying the process ID of the program (if running).
Return 0 if the service is enabled and 1 if it is not. This command does not print anything.
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:

Wait for the command to exit.
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:

Skip the check for an existing running process, and sets rc_fast=YES.
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.
Skip the checks for rcvar being set to “YES”, but performs all the other prerequisite tests.
Inhibits some verbose diagnostics. Currently, this includes messages "Starting ${name}" (as checked by check_startmsgs inside rc.subr) and errors about usage of services that are not enabled in rc.conf(5). This prefix also sets rc_quiet=YES. Note: rc_quiet is not intended to completely mask all debug and warning messages, but only certain small classes of them.

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 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 start method. The list is checked before running start_precmd.
required_files
Check for the readability of the listed files before running the start method. The list is checked before running start_precmd.
required_modules
Ensure that the listed kernel modules are loaded before running the start method. The list is checked after running start_precmd. 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 condition. 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. The list is checked after running start_precmd.
${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
A list of environment variables to run command with. Those variables will be passed as arguments to the env(1) utility unless argument_cmd is defined. In that case the contents of ${name}_env will be exported via the export(1) builtin of sh(1), which puts some limitations on the names of variables (e.g., a variable name may not start with a digit).
${name}_env_file
A file to source for environmental variables to run command with. Note: all the variables which are being assigned in this file are going to be exported into the environment of command.
${name}_fib
FIB Routing Table number to run command with. See setfib(1) for more details.
${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}_limits
Resource limits to apply to command. This will be passed as arguments to the limits(1) utility. By default, the resource limits are based on the login class defined in ${name}_login_class.
${name}_login_class
Login class to use with ${name}_limits. Defaults to “daemon”.
${name}_offcmd
Shell commands to run during start if a service is not enabled.
${name}_oomprotect
protect(1) command from being killed when swap space is exhausted. If “YES” is used, no child processes are protected. If “ALL”, protect all child processes.
${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.
${name}_prepend
Commands to be prepended to command. This is a generic version of ${name}_env, ${name}_fib, or ${name}_nice.
${name}_setup
Optional command to be run during start, restart, and reload prior to the respective argument_precmd. If the command fails for any reason it will output a warning, but execution will continue.
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:

If command is not running and checkyesno rcvar succeeds, start command.
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.
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
Runs the stop method, then the start method.
Show the PID of command, or some other script specific status operation.
Wait for command to exit.
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_service
Path to the service script being executed, in case it needs to re-invoke itself.
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.
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.

Call rc_trace to indicate that file is to be run.

However, if is_verified file fails, just return.

DebugOn will be called with tags derrived from name and rc_arg to enable tracing if any of those tags appear in DEBUG_SH.

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.
[options] file ...
Call run_rc_script for each file, unless it is already recorded as having been run.

The options are:

arg
Pass arg to run_rc_script, default is _boot set by rc(8).
break
Stop processing if any file matches any break
file ...
Used by sdot when mac_veriexec(4) is active and file is not verified.

This function limits the input from file to simple variable assignments with any non-alphanumeric characters replaced with ‘_’.

file ...
For reading in configuration files. Skip files that do not exist or are empty. Try using vdot and if that fails (the file is unverified) fall back to using safe_dot.
[-n] message
Display a start message to stdout. It should be used instead of echo(1). The display of this output can be turned off if the rc.conf(5) variable rc_startmsgs is set to “NO”.
[always]
Prevent booting to multiuser mode. If the autoboot variable is set to ‘yes’ (see rc(8) to learn more about autoboot), 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.
file ...
For reading in only verified files.

Ensure shell verify option is on. This option is only meaningful when mac_veriexec(4) is active, otherwise this function is effectively the same as dot.

Read in each file if it exists and is_verfied file is successful, otherwise set return code to 80 (EAUTH).

Restore previous state of the verify option.

[pid ...]
Wait until all of the provided pids do not exist any more, printing the list of outstanding pids every two seconds.
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.

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

rc.conf(5), debug.sh(8), rc(8)

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.

September 22, 2024 dev