This is a CPANPLUS::Shell::Default plugin that works just like
your unix shells source(1) command; it reads in a file that has
commands in it to execute, and then executes them.
A sample file might look like this:
# first, update all the source files
# find all of my modules that are on the CPAN
# test them, and store the error log
# and inform us were good to go
! print "Autotest complete, log stored; please enter your commands!"
Note how empty lines, and lines starting with a # are being skipped
in the execution.