freebsd-skq/share/man/man8/rc.8

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.\"     @(#)rc.8	8.2 (Berkeley) 12/11/93
.\" $FreeBSD$
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.Dd April 25, 2017
.Dt RC 8
.Os
.Sh NAME
.Nm rc
.Nd command scripts for auto-reboot and daemon startup
.Sh SYNOPSIS
.Nm
.Nm rc.conf
.Nm rc.conf.local
.Nm rc.d/
.Nm rc.firewall
.Nm rc.local
.Nm rc.shutdown
.Nm rc.subr
.Sh DESCRIPTION
The
.Nm
utility is the command script which controls the automatic boot process
after being called by
.Xr init 8 .
The
.Nm rc.local
script contains commands which are pertinent only
to a specific site.
Typically, the
.Pa /usr/local/etc/rc.d/
mechanism is used instead of
.Nm rc.local
these days but if
you want to use
.Nm rc.local ,
it is still supported.
In this case, it should source
.Pa /etc/rc.conf
and contain additional custom startup code for your system.
The best way to handle
.Nm rc.local ,
however, is to separate it out into
.Nm rc.d/
style scripts and place them under
.Pa /usr/local/etc/rc.d/ .
The
.Nm rc.conf
file contains the global system configuration information referenced
by the startup scripts, while
.Nm rc.conf.local
contains the local system configuration.
See
.Xr rc.conf 5
for more information.
.Pp
The
.Nm rc.d/
directories contain scripts which will be automatically
executed at boot time and shutdown time.
.Pp
The sysrc(8) command provides a scripting interface to modify system
config files.
.Ss Operation of Nm
.Bl -enum
.It
If autobooting, set
.Va autoboot Ns = Ns Li yes
and enable a flag
.Pq Va rc_fast Ns = Ns Li yes ,
which prevents the
.Nm rc.d/
scripts from performing the check for already running processes
(thus speeding up the boot process).
This
.Va rc_fast Ns = Ns Li yes
speedup will not occur when
.Nm
is started up after exiting the single-user shell.
.It
Determine whether the system is booting diskless,
and if so run the
.Pa /etc/rc.initdiskless
script.
.It
Source
.Pa /etc/rc.subr
to load various
.Xr rc.subr 8
shell functions to use.
.It
Load the configuration files.
.It
Determine if booting in a jail,
and add
.Dq Li nojail
(no jails allowed) or
.Dq Li nojailvnet
(only allow vnet-enabled jails) to the list of KEYWORDS to skip in
.Xr rcorder 8 .
.It
If the file
.Va ${firstboot_sentinel}
does not exist, add
.Dq Li firstboot
to the list of KEYWORDS to skip in
.Xr rcorder 8 .
.It
Invoke
.Xr rcorder 8
to order the files in
.Pa /etc/rc.d/
that do not have a
.Dq Li nostart
KEYWORD (refer to
.Xr rcorder 8 Ns 's
.Fl s
flag).
.It
Call each script in turn using
.Fn run_rc_script
(from
.Xr rc.subr 8 ) ,
which sets
.Va $1
to
.Dq Li start ,
and sources the script in a subshell.
If the script has a
.Pa .sh
suffix then it is sourced directly into the current shell.
Stop processing when the script that is the value of the
.Va $early_late_divider
has been run.
.It
Check again to see if the file
.Va ${firstboot_sentinel}
exists (in case it is located on a newly mounted file system)
and adjust the list of KEYWORDs to skip appropriately.
.It
Re-run
.Xr rcorder 8 ,
this time including the scripts in the
.Va $local_startup
directories.
Ignore everything up to the
.Va $early_late_divider ,
then start executing the scripts as described above.
.It
If the file
.Va ${firstboot_sentinel}
exists, delete it.
If the file
.Va ${firstboot_sentinel}-reboot
also exists (because it was created by a script), then delete it and reboot.
.El
.Ss Operation of Nm rc.shutdown
.Bl -enum
.It
Source
.Pa /etc/rc.subr
to load various
.Xr rc.subr 8
shell functions to use.
.It
Load the configuration files.
.It
Invoke
.Xr rcorder 8
to order the files in
.Pa /etc/rc.d/
and the
.Va $local_startup
directories
that have a
.Dq Li shutdown
KEYWORD (refer to
.Xr rcorder 8 Ns 's
.Fl k
flag),
reverse that order, and assign the result to a variable.
.It
Call each script in turn using
.Fn run_rc_script
(from
.Xr rc.subr 8 ) ,
which sets
.Va $1
to
.Dq Li stop ,
and sources the script in a subshell.
If the script has a
.Pa .sh
suffix then it is sourced directly into the current shell.
.El
.Ss Contents of Nm rc.d/
.Nm rc.d/
is located in
.Pa /etc/rc.d/ .
The following file naming conventions are currently used in
.Nm rc.d/ :
.Bl -tag -width ".Pa ALLUPPERCASE" -offset indent
.It Pa ALLUPPERCASE
Scripts that are
.Dq placeholders
to ensure that certain operations are performed before others.
In order of startup, these are:
.Bl -tag -width ".Pa NETWORKING"
.It Pa NETWORKING
Ensure basic network services are running, including general
network configuration.
.It Pa SERVERS
Ensure basic services
exist for services that start early (such as
.Pa nisdomain ) ,
because they are required by
.Pa DAEMON
below.
.It Pa DAEMON
Check-point before all general purpose daemons such as
.Pa lpd
and
.Pa ntpd .
.It Pa LOGIN
Check-point before user login services
.Pa ( inetd
and
.Pa sshd ) ,
as well as services which might run commands as users
.Pa ( cron
and
.Pa sendmail ) .
.El
.It Pa foo.sh
Scripts that are to be sourced into the current shell rather than a subshell
have a
.Pa .sh
suffix.
Extreme care must be taken in using this, as the startup sequence will
terminate if the script does.
.It Pa 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
.Fn stop_boot
function (from
.Xr rc.subr 8 ) .
.El
.Pp
Each script should contain
.Xr rcorder 8
keywords, especially an appropriate
.Dq Li PROVIDE
entry, and if necessary
.Dq Li REQUIRE
and
.Dq Li BEFORE
keywords.
.Pp
Each script is expected to support at least the following arguments, which
are automatically supported if it uses the
.Fn run_rc_command
function:
.Bl -tag -width ".Cm restart" -offset indent
.It Cm start
Start the service.
This should check that the service is to be started as specified by
.Xr 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
.Fx
scripts if the system is starting directly to multi-user mode, to
speed up the boot process.
If
.Cm forcestart
is given, ignore the
.Xr rc.conf 5
check and start anyway.
.It Cm stop
If the service is to be started as specified by
.Xr rc.conf 5 ,
stop the service.
This should check that the service is running and complain if it is not.
If
.Cm forcestop
is given, ignore the
.Xr rc.conf 5
check and attempt to stop.
.It Cm restart
Perform a
.Cm stop
then a
.Cm start .
.It Cm 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).
.It Cm describe
Print a short description of what the script does.
.It Cm extracommands
Print the script's non-standard commands.
.It Cm 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.
.It Cm enabled
Return 0 if the service is enabled and 1 if it is not.
This command does not print anything.
.It Cm rcvar
Display which
.Xr rc.conf 5
variables are used to control the startup of the service (if any).
.El
.Pp
If a script must implement additional commands it can list them in
the
.Va extra_commands
variable, and define their actions in a variable constructed from
the command name (see the
.Sx EXAMPLES
section).
.Pp
The following key points apply to old-style scripts in
.Pa /usr/local/etc/rc.d/ :
.Bl -bullet
.It
Scripts are only executed if their
.Xr basename 1
matches the shell globbing pattern
.Pa *.sh ,
and they are executable.
Any other files or directories present within the directory are silently
ignored.
.It
When a script is executed at boot time, it is passed the string
.Dq Li start
as its first and only argument.
At shutdown time, it is passed the string
.Dq Li stop
as its first and only argument.
All
.Nm 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.
.It
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
.Pa 100.foo
would be executed before
.Pa 200.bar ;
without the numeric prefixes the opposite would be true.
.It
The output from each script is traditionally a space character,
followed by the name of the software package being started or shut down,
.Em without
a trailing newline character (see the
.Sx EXAMPLES
section).
.El
.Sh SCRIPTS OF INTEREST
When an automatic reboot is in progress,
.Nm
is invoked with the argument
.Cm autoboot .
One of the scripts run from
.Pa /etc/rc.d/
is
.Pa /etc/rc.d/fsck .
This script runs
.Xr fsck 8
with option
.Fl p
and
.Fl F
to
.Dq 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
.Cm autoboot
is not set, when going from single-user to multi-user mode for example,
the script does not do anything.
.Pp
The
.Pa /etc/rc.d/local
script can execute scripts from multiple
.Nm rc.d/
directories.
The default location includes
.Pa /usr/local/etc/rc.d/ ,
but these may be overridden with the
.Va local_startup
.Xr rc.conf 5
variable.
.Pp
The
.Pa /etc/rc.d/serial
script is used to set any special configurations for serial devices.
.Pp
The
.Nm rc.firewall
script is used to configure rules for the kernel based firewall
service.
It has several possible options:
.Pp
.Bl -tag -width ".Ar filename" -compact -offset indent
.It Cm open
will allow anyone in
.It Cm client
will try to protect just this machine
.It Cm simple
will try to protect a whole network
.It Cm closed
totally disables IP services except via
.Pa lo0
interface
.It Cm UNKNOWN
disables the loading of firewall rules
.It Ar filename
will load the rules in the given filename (full path required).
.El
.Pp
Most daemons, including network related daemons, have their own script in
.Pa /etc/rc.d/ ,
which can be used to start, stop, and check the status of the service.
.Pp
Any architecture specific scripts, such as
.Pa /etc/rc.d/apm
for example, specifically check that they are on that architecture
before starting the daemon.
.Pp
Following tradition, all startup files reside in
.Pa /etc .
.Sh FILES
.Bl -tag -compact -width Pa
.It Pa /etc/rc
.It Pa /etc/rc.conf
.It Pa /etc/rc.conf.local
.It Pa /etc/rc.d/
.It Pa /etc/rc.firewall
.It Pa /etc/rc.local
.It Pa /etc/rc.shutdown
.It Pa /etc/rc.subr
.It Pa /var/run/dmesg.boot
.Xr dmesg 8
results soon after the
.Nm
process begins.
Useful when
.Xr dmesg 8
buffer in the kernel no longer has this information.
.El
.Sh EXAMPLES
The following is a minimal
.Nm rc.d/
style script.
Most scripts require little more than the following.
.Bd -literal -offset indent
#!/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"
.Ed
.Pp
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.
.Bd -literal -offset indent
#!/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"
.Ed
.Pp
As all processes are killed by
.Xr init 8
at shutdown, the explicit
.Xr kill 1
is unnecessary, but is often included.
.Sh SEE ALSO
.Xr kill 1 ,
.Xr rc.conf 5 ,
.Xr init 8 ,
.Xr rc.subr 8 ,
.Xr rcorder 8 ,
.Xr reboot 8 ,
.Xr savecore 8 ,
.Xr sysrc 8
.Sh HISTORY
The
.Nm
utility appeared in
.Bx 4.0 .