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RC.SUBR (8) | | Unix Manual Pages | :man


rc.subr - functions used by system shell scripts


See Also


. /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_rc_config command
mount_critical_filesystems type
rc_usage command ...
reverse_list item ...
run_rc_command argument
run_rc_script file argument
set_rcvar [base]
wait_for_pids [pid ...]
warn message


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
.Nx and it is intended that they remain synced between the two projects. With that in mind there are several variable definitions that can help in this regard. They are:

Its value will be either "FreeBSD" or "NetBSD", depending on which OS it is running on.
The path to the sysctl(8) command.
The path and argument list to display only the sysctl(8) values instead of a name = value pair.
The path and argument to write or modify sysctl(8) values.

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.

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, 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.
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.
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, usually /etc/rc.d/name. 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_rc_config command
Source in the 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.
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
.Sm off "[fast| force | one]".
.Sm on
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
.Fx 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).
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.
command Full path to the command. Not required if argument _cmd is defined for each supported keyword.
Optional arguments and/or shell directives for command.
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/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.
Check for the existence of the listed directories before running the default start method.
Check for the readability of the listed files before running the default start method.
Perform checkyesno on each of the list variables before running the default start method.
Directory to cd to before running command, if ${name}_chroot is not provided.
Directory to chroot(8) to before running command. Only supported after /usr is mounted.
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.
nice(1) level to run command as. Only supported after /usr is mounted.
User to run command as, using chroot(8). if ${name}_chroot is set, otherwise uses su(1). Only supported after /usr is mounted.
Group to run the chrooted command as.
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 does not 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:











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.
set_rcvar [base]
Set the variable name required to start a service. In
.Fx a daemon is usually controlled by an rc.conf(5) variable consisting of a daemon’s name postfixed by the string ""_enable"". This is not the case in
.Nx . When the following line is included in a script


This function will use the value of the $name variable, which should be defined by the calling script, to construct the appropriate rc.conf(5) knob. If the base argument is set it will use base instead of $name.

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.


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


rc.conf(5), rc(8)



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