Learning Perl, 7th Edition

Chapter 13. Directory Operations

The files you created in Chapter 12 were generally in the same place as your program. But modern operating systems let you organize files into directories. Perl lets you manipulate these directories directly, in ways that are even fairly portable from one operating system to another.

Perl tries very hard to act the same no matter which system it runs on. Despite that, this chapter certainly shows Perl’s preference toward its Unix history. If you are using Windows, you should look at the Win32 distribution. Those modules provide hooks to the Win32 API.

The Current Working Directory

Your program runs with a working directory. This is the default directory for everything your program does.

With the Cwd module (part of the Standard Library), you can see what that directory is. Try this program, which we’ll call show_my_cwd:

use v5.10;
use Cwd;
say "The current working directory is ", getcwd();

This should be the same directory that you’d get if you ran pwd in the Unix shell or cd (with no argument) in the Windows command shell. While you’re practicing Perl with this book, you’re most likely working in the same directory that holds your program.

When you open a file using a relative path (one that does not give the complete path from the top of the filesystem tree), Perl interprets that relative path starting at the current directory. Say that your current working directory is /home/fred. When you run this line of code to read a file, Perl looks for /home/fred/relative/path.txt ...