rc.subr
—
functions used by system shell scripts
rc.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 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.
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 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.
basename
file
[suffix] Just like
basename(1), except
implemented using shell built-in commands, and usable before the
/usr/bin direcory is available.
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 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 variable.
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.
dirname
file Just like
dirname(1), except
implemented using shell built-in commands, and usable before the
/usr/bin direcory is available.
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.
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
control of rc(8), then the
command is executed without special treatment.
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 context 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 console.
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 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
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 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.
- 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 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
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 variables 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 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 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
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:
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.
- 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 appearance 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”.
- /etc/rc.subr
- The
rc.subr
file resides in
/etc.
rc.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.