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rc(1M) rc(1M)

NAME

rc - general purpose sequencer invoked upon entering new run level

SYNOPSIS

/sbin/rc

DESCRIPTION

The rc shell script is the general sequencer invoked upon entering a new run level via the init N com-

mand (where N equals 0-6). The script /sbin/rc is typically invoked by the corresponding entry in the

ﬁle /etc/inittab as follows:

sqnc:123456:wait:/sbin/rc </dev/console >/dev/console 2>&1

/sbin/rc

is the startup and shutdown sequencer script. There is only one sequencer script and it han-

dles all of the sequencer directories. This script sequences the scripts in the appropriate sequencer direc-

tories in alphabeticalorder as deﬁned by the shell and invokes them as either startup or kill scripts.

If a transition from a lower to a higher run level (i.e., init state) occurs, the start scripts for the new run

level and all intermediate levels between the old and new level are executed. If a transition from a higher

to a lower run level occurs, the kill scripts for the new run level and all intermediate levels between the old

and new level are executed.

If a start script link (e.g., /sbin/rcN.d/S123test) in sequencer N has a stop action, the correspond-

ing kill script should be placed in sequencer N-1 (e.g., /sbin/rcN-1.d/K200test).

Actions started

in level N should be stopped in level N

-1. This way, a system shutdown (e.g., transition from level 3

directly to level 0) will result in all subsystems being stopped.

Start and Kill Scripts

In many cases, a startup script will have both a start and a kill action. For example, the inetd script starts

the Internet daemon in the start case, and kills that process in the stop case. Instead of two separate

scripts, only one exists, which accepts both the

start and stop arguments and executes the correct code.

In some cases, only a start action will be applicable. If this is the case, and if the

stop action is speciﬁed,

the script should produce a usage message and exit with an error. In general, scripts should look at their

arguments and produce error messages if bad arguments are present. When a script executes properly, it

must exit with a return value of zero. If an error condition exists, the return value must be nonzero.

Naming Conventions

The startup and shutdown scripts (referred to as startup scripts hereafter) exist in the

/sbin/init.d

directory, named after the subsystem they control. For example, the /sbin/init.d/cron

script con-

trols starting up the

cron daemon. The contents of sequencer directories consist of symbolic links to

startup scripts in /sbin/init.d . These symbolic links must follow a strict naming convention, as noted

in the various ﬁelds of this example:

/sbin/rc2.d/S060cron

where the ﬁelds are deﬁned as follows:

rc2.d The sequencer directory is numbered to reﬂect the run level for which its contents will

be executed. In this case, start scripts in this directory will be executed upon entering

run level 2 from run level 1, and kill scripts will be executed upon entering run level 2

from run level 3.

S The ﬁrst character of a sequencer link name determines whether the script is exe-

cuted as a start script (if the character is S), or as a kill script (if the character is

K).

060 A three digit number is used for sequencing scripts within the sequencer directory.

Scripts are executed by type (start or kill) in alphabeticalorder as deﬁned by the shell.

Although it is not recommended, two scripts may share the same sequence number.

cron The name of the startup script follows the sequence number. The startup script name

must be the same name as the script to which this sequencer entry is linked. In this

example, the link points to /sbin/init.d/cron.

Note that short ﬁle name systems require ﬁle names of 14 or less characters. This

means that the fourth ﬁeld is limited to 10 or fewer characters.

Scripts are executed in alphabetical order. The entire ﬁle name of the script is used

for alphabeticalordering purposes.

Section 1M−−688 − 1 − HP-UX Release 11i: December 2000

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