Perl is a high level programming language that is often used for text and file manipulation. It is most often used as a scripting language similar to Python.
Perl is a feature-rich programming language with over 26 years of development. The latest released version is Perl 5. Perl 5 runs on over 100 platforms from portables to mainframes and is suitable for both rapid prototyping and large scale development projects. There are precompiled versions for Windows, MacOS X, Linux and nearly all other forms of Unix OS. Perl can be as simple to write as a shell scripting language to a complex application development language. Generally Perl is thought of an an Interpretive language using the Perl program to interpret and execute the source code, however, internally Perl compiles the source into a tokenized binary form that is then interpreted. This offers better performance that a pure interpreter. It is also possible to convert a Perl source file into an executable using Perl2exe or another program such as PerlCC that converts Perl source into C source for compiling. Perl can also be used as a command line tool to do quick conversions using regular expressions.
Perl is easily extendible using over 25,000 open source modules available from the Comprehensive Perl Archive Network. There are many devoted specifically to eBook parsing or generation. Go to the CPAN site and search for eBook or ePub or the specific format you are interested in.