The Perl Shell (psh) combines aspects of bash and other shells with
the power of Perl scripting. It aspires to be your primary
login shell.

WHERE IT CAME FROM:

Numerous times when developing Perl code, the author wished for an
interactive Perl execution environment in which to try out code
snippets. After some looking around, there didn't appear to be a
handy solution that acted enough like a shell to be satisfactory.
It all might have ended (or rather not bugun) here except that while
discussing the idea at lunch with his friend Denny Dahl
the pressure finally became too much to bear. That evening, version 0.001
of the Perl Shell was born.