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]

DebugOn tag ...

DebugOff tag ...

debug message

dot file ...

err exitval message

force_depend name

info message

is_verified file

load_kld [-e regex] [-m module] file

load_rc_config [flag] [service]

load_rc_config_var name var

mount_critical_filesystems type

rc_log message

rc_trace level message

rc_usage command ...

reverse_list item ...

run_rc_command argument

run_rc_script file argument

run_rc_scripts [options] file ...

safe_dot file ...

sdot file ...

startmsg [-n] message

vdot file ...

wait_for_pids [pid ...]

warn message

DESCRIPTION

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:

backup_file 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:

add

file is now being backed up by or possibly re-entered into this backup mechanism. current is created.

update

file has changed and needs to be backed up. If current exists, it is copied to backup and then file is copied to current.

remove

file is no longer being tracked by this backup mechanism. 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: var should be a variable name, not its value; checkyesno will expand the variable by itself.

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.

DebugOn 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.

DebugOff 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.

debug 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.

dot 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.

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.

force_depend 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.

is_verified 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).

info 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.

load_kld [-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.

load_rc_config [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:

-s

use sdot to read configuration, because we want verified configuration or to use safe_dot to read an unverified configuration.

-v

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.

load_rc_config_var 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.

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.

rc_log 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] $*"

rc_trace 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.

rc_usage command ...

Print a usage message for $0, with commands being the list of valid arguments prefixed by “[fast|force|one|quiet]”.

reverse_list item ...

Print the list of items in reverse order.

run_rc_command 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

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.

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 is not.

restart

Perform a stop then a start. Defaults to displaying the process ID of the program (if running).

enabled

Return 0 if the service is enabled and 1 if it is not. This command does not print anything.

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.

quiet

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:

Argument	Default method
start
stop
reload
restart
status
poll
rcvar

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.

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 derived from name and rc_arg to enable tracing if any of those tags appear in DEBUG_SH.

run_rc_script executes file unless:

1. file ends in .sh and lives in /etc/rc.d.

2. file appears to be a backup or scratch file (e.g., with a suffix of ~, #, .OLD, ,v, or .orig).

3. file is not executable.

run_rc_scripts [options] file ...

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

The options are:

--arg arg

Pass arg to run_rc_script, default is _boot set by rc(8).

--break break

Stop processing if any file matches any break

safe_dot 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 ‘_’.

sdot 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.

startmsg [-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”.

stop_boot [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.

vdot 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.

wait_for_pids [pid ...]

Wait until all of the provided pids do not 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.

FILES

/etc/rc.subr

The rc.subr file resides in /etc.

SEE ALSO

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

HISTORY

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.