Hi Denys ! >> Not signal. A location/file in shared memory. Handled outside >> of init. The usual way to pass information to such kind of >> routines/scripts in Unix like systems. > >I wasn't aware it is a common practice. >For example, who does this?
I started working with Unix like systems at the end of the 1980s and worked on big Machines like Data General, Honeywell Bull down to small process controlling machines. On many of those machines either a RUNLEVEL like information is used to determine type of system shutdown or an information passed outside the init process. I do not know if there are standards on how to do this. It is just what I found to be used on many systems. >Restart action runs after shutdown actions finish. >I thought usually after shutdown actions most stuff >is unmounted or remounted ro. This might complicate >parameter passing over filesystem... Using files on shared memory is newer practice and not so problematic as you may assume. /etc/fstab knows about a mount parameter called auto. Only those file systems are mounted/umounted in an automatic process. Other systems may be hold active during shutdown. And what matters mounting info readonly? The final script just reads the information, so any file written to the root system may be appropriate. As the file needs cleaning on startup it is usually written at a location which gets cleared on system startup (eg. /var/run). Beside this there is another long standing practice to pass an information through a named pipe (fifo). The information is really short and written to the named pipe. The system startup opens the read side of the pipe but never read info. The final shutdown script read info from the pipe, which could be considered a shared memory information (as it is passed through memory resources). All this is not Linux, just Unix like machines. Linux has been more conservative and most likely used the RUNLEVEL value passed via telinit. -- Harald _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
