This screencast is showing how to use the command line debugger of perl to explore Perl.

As you might know you can run perl code on the command line without even creating a script using the -e flag:

$ perl -e "print 42"

The same way you can also run the a code that consists of the number 1 only, that of course won't do anything:

$ perl -e 1

Except that we could include the -d flag and that would run that code in the debugger

$ perl -d -e 1

Because we can combine some of the command line flags, we can also write this:

$ perl -de1