Hi all, I have the following script written according to what the perl manual for $> and $< explicitly gives as an example: 
    #!/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";

[download]
I have setuid-perl installed and run chmod ugo+xs <script>. The file is owned by a user with uid 15001 When I run this script from a different user account (with uid 1020) with Ubuntu 8.04 I get: 
    Perl version: 5.008008
    UIDs real 1020       effective 15001
    UIDs real 15001       effective 1020
    UIDs real 1020       effective 15001
    UIDs real 15001       effective 1020

[download]
All hunky dory and just what I want: the uid and euid swap quite nicely. However when I run this from a new Ubuntu with perl 5.10 I get: 
    Perl version: 5.010000
    UIDs real 1020       effective 15001
    UIDs real 1020       effective 1020
    UIDs real 1020       effective 1020
    UIDs real 1020       effective 1020

[download]
Not what I want :( Once the ids have been set to one value it becomes impossible to get the other value back. Does anyone know what is going on here - or know of a workaround? I've googled every combination of terms I can think of, but not found any suggestions. Thanks, I.

In reply to setuid script won't behave in 5.10, but did in 5.8 by isidore

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