How to tell if system shutdown is in process
How to tell if system shutdown is in process
- Subject: How to tell if system shutdown is in process
- From: Jerry Krinock <email@hidden>
- Date: Tue, 22 Mar 2011 15:45:53 -0700
I have a command-line tool which can be started automatically by launchd. Sometimes, it can start a task which takes about 30 seconds, and if this happens while the system is being shut down, it may be killed before the task completes, causing unexpected results.
In the man page for shutdown, I read:
"Upon shutdown, all running processes are sent a SIGTERM followed by a SIGKILL. The SIGKILL will follow the SIGTERM by an intentionally indeterminate period of time. Programs are expected to take only enough time to flush all dirty data and exit."
Fair enough. However, I'd like to know as early as possible when shutdown has commenced, so I can avoid starting any long-winded tasks. If all running processes receive this SIGTERM quickly upon shutdown commencement, then I think that installing a signal handler for SIGTERM would be an optimal solution.
Do all running processes receive this SIGTERM quickly upon shutdown commencement?
If, on the other hand, SIGTERM messages are sent to processes randomly over many seconds, is there any other way I could get a leg up by checking to see if the system is currently in the process of shutting down?
Thanks,
Jerry Krinock _______________________________________________
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