Just using the first set of paths, here's a solution:

use strict;

my @types = (
    qr!^/[hH]ome/([^/]+)!,
    qr!^/Users/people/([^/]+)!,
    qr!^/export/home/([^/]+)!
);

while (my $path = <DATA>) {
    my ($user) = map { $path =~ $_ ? $1 : () } @types;
    print $user, $/;
}

__DATA__
/home/user1/public_html/cgi-bin/dir
/Users/people/user2/html/cgi-bin/directory
/Home/user3/public/cgi-bin/place
/export/home/user4/www/cgi-bin/dir
[download]