At 2020-05-02T10:07:20+0100, Ralph Corderoy wrote: > Hi Branden, > > > It seems like the main difference between our signal handlers is that > > you do not reset the handler, and rely on exiting with a status > > greater than 127 to notify the shell that the process was killed with > > a signal. I'm not sure that is reliable, or supposed to be. > > Do you mean distinguish these two cases from a shell script using `$?'? > > $ sh -c 'kill $$'; echo $? > Terminated > 143 > $ sh -c 'exit 143'; echo $? > 143 > $
Yes. I suppose, without checking any Unix's implementation details, that these may differ because the fact that a process has been signaled could be in a part of the wait-status (which is an int, wider than a byte) that is not exposed as part of the exit integer. I suppose that in practice it may be that bit 7 of wstatus is typically the bit returned by the WIFSIGNALED() macro, but I wouldn't want to stake my life on it. The more of the Austin Group's time I see taken up with bizarre implementation differences in the shell, the more paranoid and less certain I get about what is reliable. Regards, Branden
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