Hi madtoperl,

A oneliner you say?

$ echo abc.def.ghi.jkl.mno | \
  perl -lne 'print join ".", reverse split /\./'
mno.jkl.ghi.def.abc
[download]

Update: Golfed a tiny bit. If your shell causes you trouble with the backslash, try -F"[.]" instead.

$ echo abc.def.ghi.jkl.mno | \
  perl -F'\.' -lpe'$_=join".",reverse@F'
mno.jkl.ghi.def.abc
[download]

Documentation of the switches is in perlrun.

Regards,
-- Hauke D