Author: Stan Eisenstat
Subject: Re: [Cs323] status
Date: Monday, 16 Nov 2020, 07:21:43

    > Message Posted By: Unknown
    >
    > Why is the STATUS macro needed? ...

To extract information from the status returned by
wait() or waitpid() in an 8-bit format that includes
the signal that terminated the process (if any) and the
low-order byte of the value returned by main() or passed
to exit(), yet can be used as an exit status.
=====

    >                            ...  when does it matter for execution of a
    > command that the status >= 128? ...

Any nonzero status indicates that the command failed.
=====

    >                            ...  Wouldnt the program have already exited by
    > then because this means that one of the system calls failed?

No.  It is the parent process that needs to know the
value returned by STATUS().
=====

    > Also, just to clarify, does a status between 1 and 127 mean a failed
    > process but it wasn't killed?

Yes.

--Stan-