A lot of your things you don't understand are wrappers around or versions of underlying standard *NIX system calls and/or library functions. A good reference such as APUE (ISBN 9780321525949) will explain those. The perl version will usually do the same thing (in a perl-y way; taking a handle rather than a file descriptor (e.g.)).

Additionally The Perl Cookbook (ISBN 9780596003135), while a little long in the tooth, also provides more of these simple samples that you're wanting.