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Issue 55

From Issue #55
November 1998

Nov 01, 1998  By Alessandro Rubini
 in
init is the driving force that keeps our Linux box alive and is also the one that can put it to death. This article summarizes why init is so powerful and how you can instruct it to behave differently from its default behaviour. (Yes, init is powerful, but the superuser rules over init.)
Debian 2.0

At the time of writing, Debian 2.0 is being released to the public, and I suspect it will be in wide use by the time you read this article.

Although the structure of system initialization is the same, it is interesting to note that the developers managed to make it faster. Instead of executing the files in /etc/rc2.d, the script /etc/init.d/rc can now source (read) them, without spawning another shell. Whether to execute or source them is controlled by the file name: executables whose name ends in .sh are sourced, the other ones are executed. The trick is shown in the following few lines:

case "$i" in
        *.sh)
            # Source shell script for speed.
            (
            trap - INT QUIT TSTP
            set start; . $i
            ) ;;
        *)
            # No sh extension, so fork subprocess.
            $i start ;;
   esac

The speed benefit is quite noticeable.

is a Stone Age guy who runs old hardware, rides an old bike and drives an old car. He enjoys hunting (using grep) through his (old) file system for information that can be converted from C language to English or Italian. If he's not reading e-mail at rubini@linux.it, then he's doing something else.

______________________

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