'Not a directory error' is coming because here localtime is a symbolic link not a directory.
using command:ls -l localtime gives: lrwxrwxrwx. 1 root root 27 Oct 31 19:00 localtime -> /usr/share/zoneinfo/Etc/UTC
as output. Here 'l' in the begining means that localtime is a symbolic link.
For the command : ln -sf /usr/share/zoneinfo/Eire localtime to work,
delete the existing symbolic link localtime as : rm localtime
then use command : better see This link