Sys::Utmp provides a vaguely object oriented interface to the Unix user
accounting file ( sometimes /etc/utmp or /var/run/utmp). Whilst it would
prefer to use the getutent() function from the systems C libraries it will
attempt to provide its own if they are missing.

This may not be the module that you are looking for - there is a User::Utmp
which provides a different procedural interface and may well be more
complete for your purposes.