6.1.2 Operating System

6.1.2.6 Init

/sbin/init starts and forks into the background to run forever (process 1; it must always be running). init then invokes the run control (RC) scripts (in /etc for SunOS 4.X, /sbin for SunOS 5.X) to perform system checks and start the daemon processes. init runs the scripts /etc/rc.boot and /etc/rc.ip (SunOS 4.1.X) or /sbin/rcS (SunOS 5.X) which runs fsck. It then continues on with the boot sequence to run /etc/rc, /etc/rc.single, and /etc/rc.local (SunOS 4.X) or /sbin/rc2 and /sbin/rc3 (SunOS 5.X). The System V version of init reads /etc/inittab to determine the actions to take at various run levels.

IRIX 5.X has it's RC scripts in /etc and runs bcheckrc, brc, rc2, and rc3, as determined by inittab, as the appropriate run levels are reached. It uses the files in /etc/config to determine which daemons to start and the options to use for system services.

Digital UNIX has it's RC scripts in /sbin and runs bcheckrc, rc2, and rc3, via /etc/inittab, as it moves through the various run-levels. The RC scripts source the resource definitions file, /etc/rc.config to determine the values for certain system parameters and whether or not to start particular services.

Unix System Administration - 8 AUG 1996

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