& and >>

[Dan Sopher]

Regarding the following document:

 

http://perldoc.perl.org/functions/system.html

 

1.      What does ($? & 127) mean?
2.      What does $? >> 8  mean?

 

 

Example from the document:

 

    if ($? == -1) {
     print <http://perldoc.perl.org/functions/print.html>  "failed to
execute: $!\n";
    }
    elsif ($? & 127) {
     printf <http://perldoc.perl.org/functions/printf.html>  "child died
with signal %d, %s coredump\n",
         ($? & 127),  ($? & 128) ? 'with' : 'without';
    }
    else {
     printf <http://perldoc.perl.org/functions/printf.html>  "child
exited with value %d\n", $? >> 8;

}

 

Thanks in advance,

 

Dan