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On system bootup, the init process runs the /etc/rc.d/rc.sysinit script to setup the system, such as setting the clock, system font, keyboard map and checking the file systems. rc.sysinit also runs all the programs in the /etc/rc.d/rc.startup directory and then runs the /etc/rc.d/rc.local script, all with the command line parameter start.
On system shutdown, the script /etc/rc.d/rc.sysdone runs. This scripts runs all the programs in the /etc/rc.d/rc.shutdown directory and then runs the /etc/rc.d/rc.local script, all with the command line parameter stop.
All the programs in /etc/rc.d/rc.startup and /etc/rc.d/rc.shutdown are symbolic links that reference actual shell scripts or binary programs; they are run in the ASCII order of their file names. These symbolic links are named with leading numbers to help control their ordering e.g., 10.network is the symbolic link the the network startup program. The actual programs are in /etc/rc.d/init.d. Removing a symbolic link disables the program from starting up. These programs typically are shell scripts; they are commonly called initscripts.
Initscripts can be interactively invoked. The following command runs the network script /etc/rc.d/init.d/syslog with the command line option stop.
service syslog stop
All scripts use the command line options start, stop, reload, restart and status. They print a list of supported options if they are called with no option present.
The initscripts define the basic ttylinux bootup system configuration. The initscripts are configurable, to an extent; thus the bootup configuration is configurable, to an extent. The bootup system configuration is specified in ASCII text files in the /etc/sysconfig directory; this directory is intended to have only files that are read by the various initscripts. All files read by initscripts for configuration options should reside in /etc/sysconfig.