AIX Tip of the Week

New AIX Support for System V Init

Audience: Systems Administrators

Date: March 2, 2001

The AIX maintenance level adds a new /etc/rc.d directory. This directory supports the System V Init process. It has been added to AIX to make it easier to port System V applications that depend on run level. (AIX still uses the BSD style init.)

The purpose of both System V and BSD init is to start processes at boot time. The processes that are started depend on the system "run level" (AIX has "run levels" ranging from 0-9, with level 3 being default.)

In the System V init process, the startup scripts are grouped into directories by "run level." The directory names are of the form /etc/rc.d/rc${run_level}.d (For example, /etc/rc.d/rc3.d directory contains scripts for run level 3.) Each directory contains both startup/shutdown scripts. Script names that start with "K" kill processes, and script names that start with "S" start processes. The scripts are run in alphabetical order.

In practice, the startup scripts physically reside in the /etc/rc.d/init.d directory. The scripts in the /etc/rc.d/rc${run_level}.d are actually links to back to files in the <>init.d directory.

For more information on the AIX init process, see:

Bruce Spencer,