Luckily, with this method you'll never get my way of putting '.' into my $ENV{PATH}:

source '~/.dot_path'
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where ~/.dot_path contains mostly

PATH=${PATH}:.
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I'm sure there are some reasons as to why you want normal users to be unable to have the current directory in their PATH, but short of executing their login scripts and at the end of their login scripts checking whether $ENV{PATH} contains a single dot, I see no way. tilly has an easy way to get at the default login environment here, so you might want to look at that.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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