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RC(8) |
FreeBSD System Manager's Manual |
RC(8) |
rc —
command scripts for auto-reboot and daemon startup
The rc utility is the command script which controls the
automatic boot process after being called by
init(8).
The rc.local script contains commands which are
pertinent only to a specific site. Typically, the
/usr/local/etc/rc.d/ mechanism is used instead of
rc.local these days but if you want to use
rc.local , it is still supported. In this case, it
should source /etc/rc.conf and contain additional
custom startup code for your system. The best way to handle
rc.local , however, is to separate it out into
rc.d/ style scripts and place them under
/usr/local/etc/rc.d/. The
rc.conf file contains the global system configuration
information referenced by the startup scripts, while
rc.conf.local contains the local system configuration.
See
rc.conf(5)
for more information.
The rc.d/ directories contain scripts
which will be automatically executed at boot time and shutdown time.
The
service(8)
command provides a convenient interface to manage rc.d services.
The
sysrc(8)
command provides a scripting interface to modify system config files.
Operation of rc
- If autobooting, set
autoboot=
yes and enable a
flag (rc_fast=yes ), which
prevents the rc.d/ scripts from performing the
check for already running processes (thus speeding up the boot process).
This rc_fast=yes speedup
will not occur when rc is started up after exiting
the single-user shell.
- Determine whether the system is booting diskless, and if so run the
/etc/rc.initdiskless script.
- Source /etc/rc.subr to load various
rc.subr(8)
shell functions to use.
- Load the configuration files.
- Determine if booting in a jail, and add
“
nojail ” (no jails allowed) or
“nojailvnet ” (only allow
vnet-enabled jails) to the list of KEYWORDS to skip in
rcorder(8).
- If the file ${firstboot_sentinel} does not exist,
add “
firstboot ” to the list of
KEYWORDS to skip in
rcorder(8).
- Invoke
rcorder(8)
to order the files in /etc/rc.d/ that do not have
a “
nostart ” KEYWORD (refer to
rcorder(8)'s
-s flag).
- Call each script in turn using
run_rc_script ()
(from
rc.subr(8)),
which sets $1 to
“start ”, and sources the script in a
subshell. Stop processing when the script that is the value of the
$early_late_divider has been run.
- Check again to see if the file ${firstboot_sentinel}
exists (in case it is located on a newly mounted file system) and adjust
the list of KEYWORDs to skip appropriately.
- Re-run
rcorder(8),
this time including the scripts in the
$local_startup directories. Ignore everything up to
the $early_late_divider, then start executing the
scripts as described above.
- If the file ${firstboot_sentinel} exists, delete it.
If the file ${firstboot_sentinel}-reboot also exists
(because it was created by a script), then delete it and reboot.
Operation of rc.shutdown
- Set rc_shutdown to the value of the first argument
passed to
rc.shutdown or to
“unspecified ” if no argument was
passed.
- Source /etc/rc.subr to load various
rc.subr(8)
shell functions to use.
- Load the configuration files.
- Invoke
rcorder(8)
to order the files in /etc/rc.d/ and the
$local_startup directories that have a
“
shutdown ” KEYWORD (refer to
rcorder(8)'s
-k flag), reverse that order, and assign the
result to a variable.
- Call each script in turn using
run_rc_script ()
(from
rc.subr(8)),
which sets $1 to
“faststop ”, and sources the script
in a subshell.
Contents of rc.d/
rc.d/ is located in /etc/rc.d/.
The following file naming conventions are currently used in
rc.d/ :
- ALLUPPERCASE
- Scripts that are “placeholders” to ensure that certain
operations are performed before others. In order of startup, these are:
- FILESYSTEMS
- Ensure that root and other critical file systems are mounted. This is
the default $early_late_divider.
- NETWORKING
- Ensure basic network services are running, including general network
configuration.
- SERVERS
- Ensure basic services exist for services that start early (such as
nisdomain), because they are required by
DAEMON below.
- DAEMON
- Check-point before all general purpose daemons such as
lpd and ntpd.
- LOGIN
- Check-point before user login services (inetd
and sshd), as well as services which might run
commands as users (cron and
sendmail).
- bar
- Scripts that are sourced in a subshell. The boot does not stop if such a
script terminates with a non-zero status, but a script can stop the boot
if necessary by invoking the
stop_boot () function
(from
rc.subr(8)).
Each script should contain
rcorder(8)
keywords, especially an appropriate
“PROVIDE ” entry, and if necessary
“REQUIRE ” and
“BEFORE ” keywords.
Each script is expected to support at least the following
arguments, which are automatically supported if it uses the
run_rc_command () function:
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. If
forcestart is given, ignore the
rc.conf(5)
check and start anyway.
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. If
forcestop is given,
ignore the
rc.conf(5)
check and attempt to stop.
restart
- Perform a
stop then a
start .
status
- If the script starts a process (rather than performing a one-off
operation), show the status of the process. Otherwise it is not necessary
to support this argument. Defaults to displaying the process ID of the
program (if running).
enable
- Enable the service in
rc.conf(5).
disable
- Disable the service in
rc.conf(5).
delete
- Remove the service from
rc.conf(5).
If
‘
service_delete_empty ’
is set to “YES ”,
/etc/rc.conf.d/$servicename will be deleted if
empty after modification.
describe
- Print a short description of what the script does.
extracommands
- Print the script's non-standard commands.
poll
- If the script starts a process (rather than performing a one-off
operation), wait for the command to exit. Otherwise it is not necessary to
support this argument.
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 a script must implement additional commands it can list them in
the extra_commands variable, and define their actions
in a variable constructed from the command name (see the
EXAMPLES section).
The following key points apply to old-style scripts in
/usr/local/etc/rc.d/:
- Scripts are only executed if their
basename(1)
matches the shell globbing pattern *.sh, and they
are executable. Any other files or directories present within the
directory are silently ignored.
- When a script is executed at boot time, it is passed the string
“
start ” as its first and only
argument. At shutdown time, it is passed the string
“stop ” as its first and only
argument. All rc.d/ scripts are expected to handle
these arguments appropriately. If no action needs to be taken at a given
time (either boot time or shutdown time), the script should exit
successfully and without producing an error message.
- The scripts within each directory are executed in lexicographical order.
If a specific order is required, numbers may be used as a prefix to the
existing filenames, so for example 100.foo would
be executed before 200.bar; without the numeric
prefixes the opposite would be true.
- The output from each script is traditionally a space character, followed
by the name of the software package being started or shut down,
without a trailing newline character.
When an automatic reboot is in progress, rc is invoked
with the argument autoboot . One of the scripts run
from /etc/rc.d/ is
/etc/rc.d/fsck. This script runs
fsck(8)
with option -p and -F to
“preen” all the disks of minor inconsistencies resulting from
the last system shutdown. If this fails, then checks/repairs of serious
inconsistencies caused by hardware or software failure will be performed in
the background at the end of the booting process. If
autoboot is not set, when going from single-user to
multi-user mode for example, the script does not do anything.
The /etc/rc.d/local script can execute
scripts from multiple rc.d/ directories. The default
location includes /usr/local/etc/rc.d/, but these
may be overridden with the local_startup
rc.conf(5)
variable.
The /etc/rc.d/serial script is used to set
any special configurations for serial devices.
The rc.firewall script is used to
configure rules for the kernel based firewall service. It has several
possible options:
open
- will allow anyone in
client
- will try to protect just this machine
simple
- will try to protect a whole network
closed
- totally disables IP services except via lo0
interface
UNKNOWN
- disables the loading of firewall rules
- filename
- will load the rules in the given filename (full path required).
Most daemons, including network related daemons, have their own
script in /etc/rc.d/, which can be used to start,
stop, and check the status of the service.
Any architecture specific scripts, such as
/etc/rc.d/apm for example, specifically check that
they are on that architecture before starting the daemon.
Following tradition, all startup files reside in
/etc.
- /etc/rc
-
- /etc/rc.conf
-
- /etc/rc.conf.local
-
- /etc/rc.d/
-
- /etc/rc.firewall
-
- /etc/rc.local
-
- /etc/rc.shutdown
-
- /etc/rc.subr
-
- /var/run/dmesg.boot
- dmesg(8)
results soon after the
rc process begins. Useful
when
dmesg(8)
buffer in the kernel no longer has this information.
The following is a minimal rc.d/ style script. Most
scripts require little more than the following.
#!/bin/sh
#
# PROVIDE: foo
# REQUIRE: bar_service_required_to_precede_foo
. /etc/rc.subr
name="foo"
rcvar=foo_enable
command="/usr/local/bin/foo"
load_rc_config $name
run_rc_command "$1"
Certain scripts may want to provide enhanced functionality. The
user may access this functionality through additional commands. The script
may list and define as many commands at it needs.
#!/bin/sh
#
# PROVIDE: foo
# REQUIRE: bar_service_required_to_precede_foo
# BEFORE: baz_service_requiring_foo_to_precede_it
. /etc/rc.subr
name="foo"
rcvar=foo_enable
command="/usr/local/bin/foo"
extra_commands="nop hello"
hello_cmd="echo Hello World."
nop_cmd="do_nop"
do_nop()
{
echo "I do nothing."
}
load_rc_config $name
run_rc_command "$1"
As all processes are killed by
init(8)
at shutdown, the explicit
kill(1)
is unnecessary, but is often included.
The rc utility appeared in
4.0BSD.
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