Errno3pm
System errno constants
Usage
use Errno qw(EINTR EIO :POSIX);
Overview
Errno defines and conditionally exports all the error constants defined in your system errno.h include file. It has a single export tag, :POSIX, which will export all POSIX defined error numbers.
Errno also makes %! magic such that each element of %! has a non-zero value only if $! is set to that value, eg
use Errno;unless (open(FH, "/fangorn/spouse")) {if ($!{ENOENT}) {warn "Get a wife!\n";} else {warn "This path is barred: $!";}}