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]
• debug message
• err exitval message
• force_depend name
• info message
• load_kld [-e regex] [-m module] file
• load_rc_config [service]
• load_rc_config_var name var
• mount_critical_filesystems type
• rc_usage command ...
• reverse_list item ...
• run_rc_command argument
• run_rc_script file argument
• 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.

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.

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.

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 [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.

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_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.

required_files

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

required_modules

Ensure that the listed kernel modules are loaded before running the start method. 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.

${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}_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.

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 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

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_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.

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.

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.

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), 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.