zlacker

To be able to fully comprehend Perl (even without having to embrace it), one needs a fiddle.

Perl and some of Perl's quirks will make more sense once you realise that it is deeply rooted in UNIX command line utilities, UNIX conventions and some UNIX shell defaults, except when it is not, i.e.

  - What is `$_`?

$_ follows the spirit of shell variables (such as $*, $@, $! etc., heavily used in Korn, Bourne flavours but not the C flavours), but was repurposed or – more likely – picked from a pool of vacant characters with the help of a dice roll. Kind of like how ancient Egyptians built the pyramids with the help of sophisticated cranes and machinery and then vapourised their tools with high-particle beams to leave future generations guessing «how on Earth did they manage to do that». This is one of the main criticisms of Perl.

  - What is this BEGIN block at the start of this Perl file? Why is that necessary?

Perl started out as an improvement over «awk», and BEGIN is an awk construct where it is used frequently, e.g. awk 'BEGIN { IFS=":" } { … do something … }'

  - What does chomp do when it's just on its own line, with no arguments given to it?

It follows the standard convention of UNIX utilities that expect the input to come from the standard input stream (file descriptor 0 or <file-in in the shell) when no input file name has been specified. So, when no <FILE1> given to chomp, it chomps on the standard input.