[bug-gawk] system() should return != 0 when the process is killed

[Tobia Conforto]

Hello

It looks like gawk's system() only returns bits 8 to 15 (or s>>8) of the value returned by system(3), discarding any information about the termination of the child process by a signal.

This breaks use cases like this (and probably others):

    do {
        ...
    } while (! system("sleep 10"))

where the intention is to break the loop when the user interrupts (^C) the child process.

It would arguably be better if gawk returned a composite code, as traditionally done by most shells and interpreters, for example (s&127)+128 if killed, s>>8 otherwise, as in Bash.

Other awk implementations (nawk, bwk-awk, and mawk) always return values != 0 when the child process executed by system() is killed by a signal.

-Tobia