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.\"     @(#)rc.8	8.2 (Berkeley) 12/11/93
.\"
.Dd $Mdocdate: February 10 2020 $
.Dt RC 8
.Os
.Sh NAME
.Nm rc ,
.Nm rc.firsttime ,
.Nm rc.local ,
.Nm rc.securelevel
.Nd command scripts for system startup
.Sh DESCRIPTION
.Nm rc
is the command script that is invoked by
.Xr init 8
when the system starts up.
It performs system housekeeping chores and starts up system daemons.
Additionally,
.Nm rc
is intricately tied to the
.Xr netstart 8
script, which runs commands and daemons pertaining to the network.
.Nm rc
is also used to execute any
.Xr rc.d 8
scripts defined in
.Xr rc.conf.local 8 .
The
.Nm rc.securelevel ,
.Nm rc.firsttime ,
and
.Nm rc.local
scripts hold commands which are pertinent only to a specific site.
.Pp
All of these startup scripts are controlled to some
extent by variables defined in
.Xr rc.conf 8 ,
which specify which daemons and services to run.
.Pp
Before
.Xr init 8
starts
.Nm rc ,
it sets the process priority, umask, and resource limits according to the
.Dq daemon
login class as described in
.Xr login.conf 5 .
It then starts
.Nm rc
and attempts to execute the sequence of commands therein.
.Pp
The first part of
.Nm rc
runs an
.Xr fsck 8
with option
.Fl p
to
.Dq preen
all disks of minor inconsistencies resulting
from the last system shutdown and to check for serious inconsistencies
caused by hardware or software failure.
If this auto-check and repair succeeds, then the second part of
.Nm rc
is run.
However, if the file
.Pa /fastboot
exists,
fsck will not be invoked.
The file is then removed so that fsck will be run on subsequent boots.
.Pp
The second part of
.Nm rc
then asks
.Xr rc.conf 8
for configuration variables,
mounts filesystems, saves
.Xr dmesg 8
output to the file
.Pa /var/run/dmesg.boot ,
starts system daemons,
preserves editor files,
clears the scratch directory
.Pa /tmp ,
uses
.Xr savecore 8
to save any possible core image that might have been
generated as a result of a system crash,
and relinks kernel objects in a random order.
.Pp
If at any point the boot script fails,
.Xr init 8
enters single-user mode,
allowing the superuser a shell on the console.
On exiting this mode,
init again invokes
.Nm rc ,
but this time without performing the file system preen.
.Pp
Before
.Nm rc
starts most system daemons,
.Xr netstart 8
is executed.
.Pp
.Nm rc.securelevel
is executed by
.Nm rc
to start daemons that must be run before the security level changes.
Following this,
.Nm rc
then sets the security level to '1' if it wasn't set already by
.Nm rc.securelevel .
See
.Xr securelevel 7
for the effects of setting the security level.
.Pp
If
.Nm rc.firsttime
exists, it is executed once and then deleted.
Any output is mailed to root.
.Pp
.Nm rc.local
is executed towards the end of
.Nm rc
(it is not the very last as there are a few services that must be
started at the very end).
Normally,
.Nm rc.local
contains commands and daemons that are not part of the
stock installation.
.Sh FILES
.Bl -tag -width "/etc/rc.securelevelXX" -compact
.It Pa /etc/netstart
Command script for network startup.
.It Pa /etc/rc
Command scripts for system startup.
.It Pa /etc/rc.conf
System daemon configuration database.
.It Pa /etc/rc.conf.local
Site specific daemon configuration database.
.It Pa /etc/rc.d
Directory to hold
.Xr rc.d 8
scripts.
.It Pa /etc/rc.d/rc.subr
Functions used by the
.Xr rc.d 8
scripts.
.It Pa /etc/rc.firsttime
Commands run on the first boot after creation.
.It Pa /etc/rc.local
Site specific command scripts for system startup.
.It Pa /etc/rc.securelevel
Commands run before the security level changes.
.It Pa /etc/rc.shutdown
Commands run at system shutdown.
.It Pa /etc/examples/rc.*
Examples of site specific scripts.
.It Pa /fastboot
Tells
.Nm rc
not to run
.Xr fsck 8
during the next boot.
.It Pa /var/run/dmesg.boot
Copy of
.Xr dmesg 8
saved by
.Nm rc
at boot time.
.El
.Sh SEE ALSO
.Xr sysctl.conf 5 ,
.Xr securelevel 7 ,
.Xr init 8 ,
.Xr netstart 8 ,
.Xr rc.conf 8 ,
.Xr rc.d 8 ,
.Xr rc.shutdown 8 ,
.Xr rcctl 8
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.0 .