Re: no exit status available when a command doesn't exist or fails in pipe to grep

[Andrew J. Schorr]

On Thu, Sep 09, 2021 at 01:58:59AM -0600, arnold@skeeve.com wrote:
> POSIX merely says that 
> 
> | close(expression)
> |     Close the file or pipe opened by a print or printf statement or a
> |     call to getline with the same string-valued expression. The limit on
> |     the number of open expression arguments is implementation-defined. If
> |     the close was successful, the function shall return zero; otherwise,
> |     it shall return non-zero.
> 
> This is fairly vague.  I think you're getting zero because the
> underlying pclose() (or equivalent code) succeeds, even thogh the
> command itself failed.

I could be confused, but the code in io.c:do_close() looks like it returns 0 in
POSIX mode unless the command was not found. At the end of the function, it
says:

        tmp = make_number((AWKNUM) close_redir(rp, false, how));
        rp = NULL;
        /*
         * POSIX says close() returns 0 on success, non-zero otherwise.
         * For POSIX, at this point we just return 0.  Otherwise we
         * return the exit status of the process or of pclose(), depending.
         * Down in the call tree of close_redir(), we rationalize the
         * value like we do for system().
         */
        if (do_posix) {
                unref(tmp);
                tmp = make_number((AWKNUM) 0);
        }
        return tmp;

So gawk forces the return code to 0 in POSIX mode in almost all cases.

Regards,
Andy