Feature

You Used Perl to Write WHAT?!

Every programming language has its strengths...and its weaknesses. We identify five tasks for which perl is ideally suited, and four that...well, really, shouldn't you choose something else?

The Good

Pattern matching: Perl's greatest claim to fame has always been the tight integration of regular expressions into the base language syntax. For most developers, perl was the first time they ever used a regular expression.

As a result, perl has always been the go-to language for any task that involves pattern-matching input. A typical use of this capability is to scan an input stream for name/value pairs and split them. Another is parsing log files with a fixed but variable length format. It's not for nothing that a lot of the popular log file auditing packages are written in perl.
In-place editing: Combine regular expressions with the ability to edit files "in place" from the command line, and perl makes a dandy tool for performing a batch modification on a group of files. For example, suppose you have renamed the /home/george directory to /home/curious, and want to update a few hundred scripts in the /usr/lib/yellowhat directory to point at the correct new path. The following one-liner will do just that:

# perl -i.bak -p -e "s#/home/george#/home/curious#" `find . -print`

Now, this is a fairly simple example and could have easily been done using a tool such as sed, but the important thing is that you could have used any arbitrarily complex perl program as the filter, and done highly complex manipulations. Imagine an area code getting split and having to replace a single area code with one of two depending on the original exchange in hundreds of files. In perl, it would be a snap.
A replacement for shell scripts: One of the worst things about shell scripting—whether in bash, sh or csh—is that the syntax of the scripts themselves is fairly hard to read. By using perl as a scripting language instead of a "traditional" shell, you can use much more C-like syntax without sacrificing functionality.
As a database manipulation tool: One of perl's strengths has always been the strong database interoperability through the DBI and DBD libraries. If you need to create a quick database report, or convert between a database and some other form of data storage, you can very easily whip up a little utility using perl in very short time.
As a cross-platform language: Because perl is interpreted, perl scripts don't need to be recompiled when moved from platform to platform. And because companies like ActiveState have produced strong ports of perl to platforms such as Windows, most perl programs will run without modification even if they do advanced things such as database connectivity, file system modification or network programming.