Additional Information

If you are using system to get the exit status, the normal way is to shift the $? right by 8 times

But man perlport suggest as follows

In general, do not assume the UNIX/POSIX semantics that you can shift $? right by eight to get the exit value, or that "$? & 127" would give you the number of the signal that terminated the program, or that "$? & 128" would test true if the program was terminated by a coredump. Instead use the POSIX W*() interfaces: for example, use IFEXITED($?) and WEXIT-VALUE($?) to test for a normal exit and the exit value, WIFSIGNALED($?) and WTERMSIG($?) for a signal exit and the signal.