RC.SUBR(8) BSD System Manager's Manual RC.SUBR(8)NAMErc.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]
collapse_backslash_newline
err exitval message
load_rc_config command
load_rc_config_var command var
mount_critical_filesystems type
no_rc_postprocess command [arguments]
print_rc_metadata string
print_rc_normal [-n] string
rc_usage command [...]
reverse_list item [...]
run_rc_command argument [parameters]
run_rc_script file argument
stop_boot
twiddle
wait_for_pids [pid [...]]
warn message
yesno_to_truefalse var
DESCRIPTIONrc.subr contains commonly used shell script functions which are used by
various scripts such as rc(8), and the periodic system services which are
controlled by daily.conf(5), monthly.conf(5), security.conf(5), and
weekly.conf(5).
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.
action 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 that the warning message shown by this function when var is
not set references a manual page where the user can find more
information. Its name is picked up from the rcvar_manpage vari‐
able.
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.
collapse_backslash_newline
Copy input to output, collapsing ⟨backslash⟩⟨newline⟩ to nothing,
but leaving other backslashes alone.
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.
load_rc_config command
Source in the rc.conf(5) 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.
load_rc_config_var command var
Read the rc.conf(5) variable var for command 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.
no_rc_postprocess command [arguments]
Execute the specified command with the specified arguments, in such
a way that its output bypasses the post-processor that rc(8) uses
for most commands. This implies that the output will not appear in
the /var/run/rc.log file, and will appear on the console regardless
of the value of rc_silent. This is expected to be useful for
interactive commands, and this mechanism is automatically used by
run_rc_command when a script contains the rcorder(8) keyword
“interactive”.
If invoked from a context that does not appear to be under the con‐
trol of rc(8), then the command is executed without special treat‐
ment.
print_rc_metadata string
Print the specified string in such a way that it should be handled
as meta-data by the rc(8) post-processor. If invoked from a con‐
text that does not appear to be under the control of rc(8), then
the string is discarded.
Any rc.d(8) script may invoke this function with an argument that
begins with “note:”, followed by one line of arbitrary text; the
text will be logged by rc(8) but will not be displayed on the con‐
sole.
The use of arguments that do not begin with “note:” is reserved for
internal use by rc(8) and rc.subr.
print_rc_normal [-n] string
Print the specified string in such a way that it should be handled
as normal output by the rc(8) post-processor. If invoked from a
context that does not appear to be under the control of rc(8), then
the string is printed to standard output.
If the -n flag is specified, then the string is printed without a
newline.
Intended use cases include:
· An rc.d script can use “print_rc_normal -n” to print a partial
line in such a way that it appears immediately instead of being
buffered by rc(8)'s post-processor.
· An rc.d script that is run via the no_rc_postprocess function
(so most of its output is invisible to rc(8)'s post-processor)
can use print_rc_normal to force some of its output to be seen
by the post-processor.
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 [parameter ...]
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. The optional set
of parameters is passed verbatim to the command, but not to its
pre/post hooks.
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 NetBSD 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's
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.
rcvar_manpage
The manual page containing information about rcvar.
It will be part of the warning message shown when
rcvar is undefined. Defaults to rc.conf(5).
command Full path to the command. Not required if
argument_cmd is defined for each supported keyword.
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 default start method.
required_files
Check for the readability of the listed files
before running the default start method.
required_vars
Perform checkyesno on each of the list variables
before running the default 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
List of additional or modified environment vari‐
ables to set when starting command.
${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}_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 doesn't run wait_for_pids.
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.
5. If file contains the rcorder(8) keyword “interactive”, then
the command is executed using no_rc_postprocess.
stop_boot
Prevent booting to multiuser mode. If the autoboot variable is
‘yes’, then a SIGTERM signal is sent to the parent process (which
is assumed to be rc(8)). Otherwise, the shell exits with status 1.
twiddle
Display one of the characters ‘/, -, \, |’, followed by a
backspace. Repeated calls to this function will create the appear‐
ance of a spinning symbol, as a different character is displayed on
each call. Output is to /dev/tty, so this function may be useful
even inside a script whose output has been redirected.
wait_for_pids [pid [...]]
Wait until all of the provided pids don't 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.
yesno_to_truefalse var
Change the value of the specified variable from any of the forms
acceptable to the checkyesno function, to “true” or “false”.
FILES
/etc/rc.subr The rc.subr file resides in /etc.
SEE ALSOrc.conf(5), rc(8)HISTORYrc.subr appeared in NetBSD 1.3. The rc.d(8) support functions appeared
in NetBSD 1.5. Support for the rc(8) post-processor appeared in
NetBSD 6.0.
BSD August 11, 2011 BSD
