On a testing/sid system with sysvinit-core, the script /etc/init.d/mountall-bootclean.sh (linked to /etc/rcS.d/) calls clean_tmp via clean_all from /lib/init/bootclean.sh . In this function it says "Don't clean remaining files if TMPTIME is negative or 'infinite'" Therefore, to never cleanup set TMPTIME='infinite' What is your exact setting in /etc/default/rcS ? Regards, jvp.