Does shell receive term signal during reboot and abnormal shutdown

Question

Hi I need to do some process when system goes for normal or abnormal shutdown,

Please clarify my following doubts

Does shell receives term signal during normal and abnormal shutdowns.
Can i trap and see that signal,using trap command in shell?
If so in which file i should look for this signal?

Can you define *abnormal* shutdown? Do you mean a power outage, a kernel panic or something like that? — hek2mgl, Apr 18 '15 at 12:06
Kernel panic wouldn't send signals. Power outage depends upon how power is managed (`KILL` is more likely than `TERM`). — Thomas Dickey, Apr 18 '15 at 12:14
Ok Thomas can you let me know where can i look for this signal,i'm planning to use trap command so in which file i should use trap command ? — user3446120, Apr 18 '15 at 12:22
A power outage means *power outage*. Black screen, finito. There is nothing you can handle anymore. — hek2mgl, Apr 18 '15 at 12:29
@hek2mgl so where do i receive term signal when system goes for normal reboot? I n which file i should add trap command to confirm i have received term signal — user3446120, Apr 18 '15 at 12:36

score 1 · Answer 1 · edited May 23 '17 at 11:43

As noted, in a catastrophic failure (kernel panic or power outage), one should not expect a signal to be sent to a process to provide for an orderly shutdown. If the system can provide this, it would be as documented in the particular system's shutdown, poweroff or similar command. For instance, this Linux shutdown manual page says that SIGTERM is sent first, and implies that SIGKILL will be sent later. Things may not be so orderly, of course.

These provide additional discussion on the topic:

As for which file one should try to trap the SIGTERM, that really depends upon the application. The signal would be sent to all processes, and you cannot assume or rely upon any particular order of arrival for the signals. SIGKILL cannot caught; when it arrives it is too late to do anything about it.

Does shell receive term signal during reboot and abnormal shutdown

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