Want to know more?
First and foremost, Perl comes with its own documentation system called perldoc. In case your Linux distribution complains about the perldoc command being missing, make sure you have a relevant package installed, as it may not come as a default.
Perldoc spans three areas: language manual, language reference and modules documentation. Each of these is organised into sections typically called perl<something>, and you simply run perldoc perlfoo to get the topic you are after. There are quite a few sections really, but we find ourselves opening ones more often than the others:
perlfunc – Perl functions. This includes a categorised list of what Perl can do out of the box. Handy if you’ve forgotten the syntax or are looking for the way to accomplish a simple task such as deleting a key from the hash.
perlre – Perl regular expression dialect. This covers the basics, while perlrebackslash and perlrecharclass take on escape sequences and character classes, respectively.
perlref – Perl references. Not really necessary for one-liners but a must for serious Perl programming. Also a basis for Perl objects. The perldoc command is not a mere browser. perldoc -f looks up a function by name, and perldoc -v does the same for variables. For better UX, see the web version hosted at http://perldoc.perl.org.
As for books, be sure to look at ProgrammingPerl by O’Reilly. Dubbed the ‘Camel book’, co-authored by Larry Wall, and being 1,000+ pages long, it’s what they call “a canonical Perl reference”.