System boot procedure
Debian System Boot
When booting a Debian system, the scripts referenced in /etc/rcS.d always get executed. One of these scripts is referenced by the entry /etc/rcS.d/S30procps.sh; this entry is a symlink to the script /etc/init.d/procps.sh, and it sets up the /proc/sys virtual filesystem early on in the boot process of your Debian machine. This matters to us, system administrators, because if the script is invoked with "start", it runs the following command (a.o.):
sysctl -q -p /etc/procsys.conf
(well actually the last parameter is not included in the command, but since it's the default value for the location and name of the parameter file, it's totally equivalent).
This matters to us, since there are a lot of things we can - and want to! - do with the /proc/sys filesystem. For these, see our separate page of /proc/sys recommendations. Furthermore, remember that you can reinitialize the /proc/sys filesystem with the command
(although just running sysctl -p works the same if you just want to effectuate edits to /etc/sysctl.conf :-)