Perl, an acronym for Practical Extraction and Report Language, 1 is a free, cross-platform, highlevel, open-source programming language, originally created by Larry Wall and subsequently maintained by a large web-based community of programmers. Perl is derived from the C programming language and to a lesser extent from sed, awk, grep, and the Unix shell. 2 Perl's process, file and text manipulation facilities make it particularly well suited for a wide range of tasks that econometricians face regularly, such as data transformation, validation and cleaning, and the merging of several data files. It can also be useful in simplifying other more labor-intensive and sophisticated tasks, such as the conversion of econometric code from one language to another (say, GAUSS to MATLAB), regression output processing and typesetting, preparation of bibliography files (converting ISI/BIDS to bib files), publishing of math-intensive documents on Web pages (converting L A T E Xto HTML), and the distribution of computing and storage tasks across several nodes of a computer cluster.
Perl can be obtained from the Comprehensive Perl Archive Network (CPAN) located at http://www.cpan.org/, where the source package, modules, documentation, and links to binary distributions for various platforms, including Win32 (Windows NT/95/Me/2000), Mac, and Unix/Linux, are available. Reading the documentation that comes with each distribution is essential, as each port for a given platform may be compiled from a different version of Perl. 3 The program is quite easy to install, and computers that have the Linux operating system often come with Perl already installed. Because of the high-level nature of the program, only a few lines of code are often required. More complex tasks will involve the use of existing code and Perl modules