From a shell, say Bash, is it possible to retrieve the signal number received by the application that most recently finished, if any, in a way that is similar to checking the return code of a process by printing $?.
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2Possible duplicate of Linux signals logger – JigglyNaga Nov 28 '18 at 14:47
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When a process is killed, the signal that killed it is encoded in the exit status retrieved by the parent (or child subreaper or init for orphans).
In bash, $? is 128+signum.
That's what most Bourne-like shells do, ksh93 uses 256+signum, yash 384+signum.
$? being 129 in bash either means the process was killed by signal 1 (SIGHUP) or that it did a exit(129). If it did a exit(129) however, most likely that was to report a death by SIGHUP of some process.
To get the signal name from the value of $?, run:
kill -l "$?"
That works in all Bourne-like shells whether they use 128/256/384 + signum.
See details at Default exit code when process is terminated?
Stéphane Chazelas
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