RC.SUBR(8) BSD 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
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 name
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
set_rcvar [base]
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 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:
OSTYPE
Its value will be either "FreeBSD" or "NetBSD", depending on which
OS it is running on.
SYSCTL
The path to the sysctl(8) command.
SYSCTL_N
The path and argument list to display only the sysctl(8) values
instead of a name=value pair.
SYSCTL_W
The path and argument to write or modify sysctl(8) values.
The rc.subr functions are accessed by sourcing /etc/rc.subr into the cur‐
rent 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) vari‐
able 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 neces‐
sary, 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 insensi‐
tive. 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 con‐
sists 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 mes‐
sage 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 sys‐
tem 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 match‐
ing 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 name
Source in the configuration files for name. First, /etc/rc.conf is
sourced if it has not yet been read in. Then, /etc/rc.conf.d/name
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]”.
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 ser‐
vice 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).
rcvar Display which rc.conf(5) variables are used to con‐
trol 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 per‐
forms 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.
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 run‐
ning 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 condi‐
tion. 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}_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}_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.
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 suc‐
ceeds, 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 spe‐
cific 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 environ‐
ment 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.
stop_boot [always]
Prevent booting to multiuser mode. If the autoboot variable is set
to ‘yes’, 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.
set_rcvar [base]
Set the variable name required to start a service. In FreeBSD 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 NetBSD. When the following line is included in a
script:
rcvar=`set_rcvar`
this function will use the value of the $name variable, which
should be defined by the calling script, to construct the appropri‐
ate 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.
FILES
/etc/rc.subr The rc.subr file resides in /etc.
SEE ALSOrc.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.
BSD May 18, 2007 BSD
