這和具體的發行版有關pwa
1.On Debian-like systems: on boot (the rules are defined in /etc/default/rcS).it
2.On RedHat-like systems: by age (RHEL6 it was /etc/cron.daily/tmpwatch ; RHEL7 and RedHat-like with systemd it's configured in /usr/lib/tmpfiles.d/tmp.conf, called by systemd-tmpfiles-clean.service).file
3.On Gentoo /etc/conf.d/bootmisc.
service