How can I start an interactive console for Perl, similar to the irb command for Ruby or python for Python?
There isn't an interactive console for Perl built in like Python does. You can however use the Perl Debugger to do debugging related things. You turn it on with the -d option, but you might want to check out 'man perldebug' to learn about it.
After a bit of googling, there is a separate project that implements a Perl console which you can find at http://www.sukria.net/perlconsole.html.
Hope this helps!