NAME
rc.subr —
functions used by system
shell scripts
SYNOPSIS
- .
/etc/rc.subr
- backup_file action
file current
backup
- basename file
[suffix]
- checkyesno
var
- check_pidfile
pidfile procname
[interpreter]
- check_process
procname
[interpreter]
- collapse_backslash_newline
- dirname file
- 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
DESCRIPTION
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”.
FILES
- /etc/rc.subr
- The rc.subr file resides in
/etc.
SEE ALSO
rc.conf(5),
rc(8)
HISTORY
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.