# this sets $! and $^E
unlink 'asdfasdfewtwertwevbncvbnmarewrawer';

# This wipes them both out.
# Note that test.pl contains only "1;", and $@ is undef afterwards.
eval {require "test.pl"};
print "\$\@: $@\n" if $@;

# If I comment the eval line out, this prints:
#   error?: last system error: No such file or directory
#   (error number: 2) (extended error info: The system
#   cannot find the file specified
# Otherwise it just prints:
#   error?
print "error?: ", &CheckLastSystemError(), "\n";

# Here's my sub.  Feel free to add suggestions for it also if you have any.
sub CheckLastSystemError
{
    my @message;

    # check the string value
    push @message, "$!" if $!;

    # we could check $^E here, too...    # check the number value
    my $numericTest = 0 + $!;  # force numeric context
    push @message, "(error number: $numericTest)" if $numericTest;

    # $^E is sometimes just the same as $!
    push @message, "(extended error info: $^E" if ($^E && $^E ne $!);

    if (scalar @message)
    {
        # combine @message into a string and return it
        return "last system error: @message";
    }
    else
    {
        return undef;
    }
}