Problem on capturing system Shutdown Post: 302847729

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Top Forums Programming Problem on capturing system Shutdown Post 302847729 by hakermania on Tuesday 27th of August 2013 03:48:45 PM

08-27-2013

Registered User

So if it doesn't determine whether my function is sync-safe or not, the function should run without many problems most of the time (as you see, the file is accessed nowhere inside the program, a simple sleep is being done)

The only thing that I want my real handler to do is to save one variable into one file that is closed during the whole execution of the program. That is the only place where the file is opened for writing and closed.

The variable is being updated once per second (adding one to itself), so the chance of it being accessed the wrong moment is very slight, and even if it does, I don't really care.

If I understand correctly you are advising me on how to make a function sync-safe, and thanks a lot for that, but that was not my initial question. My initial question was why the handler is not executed while it should. Function being async-unsafe has nothing to do as far as I can understand from your last reply.

And one last thing: If my disk is not writable when I receive the signal, how the heck am I going to do my cleanup? How are other linux applications do stuff like this?

hakermania

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LEARN ABOUT MINIX

shutdown

SHUTDOWN(8)						      System Manager's Manual						       SHUTDOWN(8)

NAME

       shutdown - graciously close the system down

SYNOPSIS

       shutdown [-hrRmk] [-x code] [time-specification [message]]

DESCRIPTION

       Shutdown  is a program which allows a system operator to close down the system in an nice way.  Shutdown informs the users why and when the
       system is going down.  This warning is issued 10 minutes before shutdown time and every minute in the last 5 minutes.  At this time (5 min-
       utes), shutdown creates a file /etc/nologin to prevent new users from logging in.

       Shutdown keeps a logfile of shutdowns.  Every shutdown is registered in /usr/adm/wtmp, if this file exists.  After these actions, a call is
       done to reboot(2) which actually brings the system down.

       Time-specification may be something like 15:00, 15.00, +15, or now for a shutdown at 3pm (twice), 15 minutes from now, or immediately.

       The message may be used to describe why the system is going down, it may also be typed on standard input with the -m option.

OPTIONS

       -h     This flag prevents the system from rebooting after the shutdown.	The system can now be powered off.  This is the default.

       -r     This flag indicates that the system should reboot after shutting down.

       -R     Reboot the system by resetting it.  Normally the kernel will try to return to the Boot Monitor.  With -R the system will	receive  a
	      hardware reset.

       -x code
	      Halt  the  system  and  let the Monitor execute the given code as if typed at the monitor prompt.  You can for instance use -x 'boot
	      hd0' as a very fast way to reboot "from the top."

       -m     Allows the operator to type a shutdown message on standard input, that will be added to the messages displayed on all terminals.

       -k     This option gives the possibility of terminating an already started shutdown.  This is only possible if shutdown time  has  not  yet
	      arrived.

       -C     Check  if the system crashed.  This option is not used at shutdown time, but at reboot time.  It tells if the file systems should be
	      checked by testing if the last entry in the wtmp file is a shutdown entry.  (A crude replacement for a file system clean flag.)

FILES

       /usr/adm/wtmp, /etc/nologin, /usr/adm/authlog

SEE ALSO

       reboot(2), wall(1), halt(8), boot(8).

AUTHOR

       Edvard Tuinder (v892231@si.hhs.NL)

																       SHUTDOWN(8)