runit - a UNIX process no 1
runit must be run as Unix process no 1. It performs the system's booting,
running, and shutdown in three stages:
runit runs /etc/runit/1 and waits for it to terminate. The
system's one time tasks are done here. /etc/runit/1 has full control of
/dev/console to be able to start an emergency shell if the one time
initialization tasks fail. If /etc/runit/1 crashes, or exits 100,
runit will skip stage 2 and enter stage 3.
runit runs /etc/runit/2, which should not return until system
shutdown; if it crashes, or exits 111, it will be restarted. Normally
/etc/runit/2 starts runsvdir(8). runit is able to handle
the ctrl-alt-del keyboard request in stage 2, see below.
If runit is told to shutdown the system, or stage 2 returns, it
terminates stage 2 if it is running, and runs /etc/runit/3. The systems
tasks to shutdown and possibly halt or reboot the system are done here. If
stage 3 returns, runit checks if the file /etc/runit/reboot
exists and has the execute by owner permission set. If so, the system is
rebooted, it's halted otherwise.
If runit receives the ctrl-alt-del keyboard request and the file
/etc/runit/ctrlaltdel exists and has the execute by owner permission
set, runit runs /etc/runit/ctrlaltdel, waits for it to
terminate, and then sends itself a CONT signal.
runit only accepts signals in stage 2.
If runit receives a CONT signal and the file
/etc/runit/stopit exists and has the execute by owner permission set,
runit is told to shutdown the system.
if runit receives an INT signal, a ctrl-alt-del keyboard
request is triggered.
runit-init(8), runsvdir(8), runsvchdir(8), sv(8), runsv(8), chpst(8),
Gerrit Pape <email@example.com>