Beginning Perl

Chapter 9

Files and Directories

WHAT YOU WILL LEARN IN THIS CHAPTER:

• Understanding files handling
• Working with directories
• Understanding Unicode and Unicode rules
• Useful file manipulation modules

Up to this point, except for a brief discussion of @ARGV in Chapter 3, the data in your program has been embedded in the program, which isn’t useful. In the real world, we’re constantly reading data from files, Web services, databases, and a variety of other sources. This chapter introduces you to the basics of reading and writing to files and directories.

WROX.COM CODE DOWNLOAD FOR THIS CHAPTER

The wrox.com code downloads for this chapter are found at www.wrox.com/remtitle.cgi?isbn=1118013847 on the Download Code tab. The code for this chapter is divided into the following major examples:

• .targets.txt.swp
• .tree.pl.swo
• .tree.pl.swp
• example_9_1_spies.pl
• example_9_2_tree.pl
• listing_9_1_targets.pl
• listing_9_2_reading_from_data.pl
• spies1.txt
• spies2.txt
• spies3.txt
• spies4.txt
• targets.txt

BASIC FILE HANDLING

As you probably know by now, most common operating systems have their data internally organized around files and directories. Even if the data is stored in a database, it’s probably represented as files somewhere. Perl makes it easy to read and write files, and you can see the most common ways to do that.

Opening and Reading a File

For this section, type the following into a file named targets.txt in a directory named chapter_9.

James|007|Spy Number 6|6|Ex-spy Agent 99|99|Spy with unknown ...