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RC.SUBR(8) |
FreeBSD System Manager's Manual |
RC.SUBR(8) |
rc.subr —
functions used by system shell scripts
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 .
Please, 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 that 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:
- If file ends in .sh, it
is sourced into the current shell.
- If file appears to be a backup or scratch file
(e.g., with a suffix of ~,
#, .OLD, or
.orig), ignore it.
- If file is not executable, ignore it.
- 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.
- /etc/rc.subr
- The
rc.subr file resides in
/etc.
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.
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