#!/usr/bin/perl -w
    use strict;
    print "Perl version: $]\n";
    print "UIDs real $<  \t effective $>\n";
    ($>, $<) = ($<, $>);      # swap real uid and effective uid
    print "UIDs real $<  \t effective $>\n";
    ($>, $<) = ($<, $>);      # swap real uid and effective uid
    print "UIDs real $<  \t effective $>\n";
    ($>, $<) = ($<, $>);      # swap real uid and effective uid
    print "UIDs real $<  \t effective $>\n";

##</code><code>##

    Perl version: 5.008008
    UIDs real 1020  	 effective 15001
    UIDs real 15001  	 effective 1020
    UIDs real 1020  	 effective 15001
    UIDs real 15001  	 effective 1020

##</code><code>##

    Perl version: 5.010000
    UIDs real 1020  	 effective 15001
    UIDs real 1020  	 effective 1020
    UIDs real 1020  	 effective 1020
    UIDs real 1020  	 effective 1020