$Id: KNOWNDIFF,v 4.1 1993/03/23 16:17:05 mike Exp $


                  Known differences to standard SYSV.


+ Allows extended run levels and demand states. This is an extension of
  SYSV usage and does not compromise compatibility, although the usage
  of certain run levels, particularly 5 and 6, is likely to be different
  to standard SYSV usage.

+ Standard SYSV claims that init sets the tty modes on the console when
  entering single user mode and resets them when exiting single user mode.
  This init doesn't. It expects the single user process to do whatever is
  necessary.

+ When changing run level standard SYSV init first warns processes with
  SIGTERM, pauses 5 seconds and then kills them with SIGKILL. This init
  adds a second warning. The sequence is SIGTERM, pause 5 seconds, SIGINT,
  pause 2 seconds, SIGKILL. This is required mainly because xdm (the X
  windows login manager) seems to only shut down cleanly on SIGINT.
  If at any stage init finds it has no more processes in the kill group
  init will cancel the time out, skip any remaining stages and get on with
  the job in hand.

+ Standard SYSV only executes powerfail and powerwait inittab entries
  in the single user mode S. This restriction does not exist in this init.
  Powerfail and powerwait entries are executed regardless of the their
  rstate field.

+ Under standard SYSV the terminal that executed a telinit S becomes the
  system console when single user mode is reached. This isn't (yet)
  implemented in this version of init.

+ Has an extra "ctrlaltdel" process type. These processes are invoked
  immediately init receives a SIGINT (usually from the kernel because
  someone pressed ctrlaltdel). Processes are executed in the order they
  occur in inittab and each process is waited for before continuing with
  the next. When each process has been executed init continues with
  whatever it was doing when the SIGINT occurred (unless a ctrlaltdel
  process caused a shutdown or reboot). Ctrlaldel events are logged in wtmp.
