Cisco IOS Cookbook, 2nd Edition

Perl

According to the Perl web site, “Perl is a high-level programming language with an eclectic heritage written by Larry Wall and a cast of thousands. It derives from the ubiquitous C programming language and, to a lesser extent, from sed, awk, the Unix shell, and at least a dozen other tools and languages. Perl’s process, file, and text manipulation facilities make it particularly well-suited for tasks involving quick prototyping, system utilities, software tools, system management tasks, database access, graphical programming, networking, and world wide web programming.”

Many of the scripts written in Perl these days tend to involve dynamically generating web pages. But all of the scripts in this book use Perl at the command line of either a Unix or Windows computer.

We frequently use Perl for scripting network administration functions because it is an extremely powerful and flexible language, particularly for things like pattern matching. This makes it perfect for tasks like scanning logfiles, as well as for spawning dynamic queries and formatting the output into a useful report.

Perl is available for both Unix and Windows systems. This is important because while the engineers who run most of the world’s larger networks use Unix, smaller organizations frequently don’t have any Unix expertise. So it is not uncommon to see Windows computers managing smaller networks.

Perl’s free and open distribution policy means that there is usually a good port available, even if you use a different ...