[prog] check if script parent process is "init"
johnc+linuxchix at kirriwa.net
Thu Apr 15 20:26:32 EST 2004
On Wed, Apr 14, 2004 at 06:33:14 +0200, Wolfgang Petzold wrote:
> The init process usually runs scripts in /etc/init.d/ (or a similar
> location) by calling symlinks in "runlevel directories", /etc/rc?.d/ in
Only if your distro uses SysV init. Slackware used not to do it that
way; I haven't used it for a very long time (Slackware 1.1 in about
1993 IIRC) so it might have changed since then.
> The scripts themselves can then tell by the name they were called with
> if they are run automatically or manually.
No, they can't. If they're called as /etc/init.d/rc?.d/[SK]* then
they're *probably* being run by init, but you can't guarantee that.
What's to stop me running them manually by that name? Nothing at all.
$PPID should always be set, but it won't be 1. In the SysVInit
scripts, init runs /etc/rc.d/rc which in turn runs the various startup
scripts. Using runlevel 3 as an example, /etc/inittab has one line like
this for each runlevel:
/etc/rc.d/rc contains essentially this loop (cutting out all the
# Now run the START scripts.
for i in /etc/rc$runlevel.d/S*; do
So when the scripts are run, they'll have $PPID set to the pid of the
shell which is running /etc/rc.d/rc.
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