use strict;
use English;
use File::Copy qw(cp);
use Crap qw(croak);

my ($old_euid,$old_egid);
$old_euid = $>;
$old_egid = $);

# now change the euid and egid to "user1"
$> = "23333"; # new uid 
$) = "7755"; # "user1" primary group.

croak("failed to copy ") unless ( cp("/var/tmp/srcfile","/x/tmp/dstfile") );