A lot of settings can be tweaked using magic files in /proc
(for example, /proc/sys/kernel/core_uses_pid
which names core dump files with the pid).
Which settings are preserved across reboots and which ones do I need to refresh every time?
Nothing in /proc is directly preserved across reboots. The /proc filesystem is a 'pseudo' filesystem that reflects state inside the running kernel and isn't a reflection of state on any persistent storage medium.
Some stuff has the impression of being preserved because scripts in /etc/init.d/ (or /etc/rc.d, or whatever init-script convention your system uses) that are run at startup will set values in /proc. Try: grep -r '/proc' /etc/init.d/*
sysctl -w
is equivalent to writing to /proc/sys/
, just append kernel.core_uses_pid = whatever
to your /etc/sysctl.conf
file.