Linux® Programming by Example

Chapter 2. Arguments, Options, and the Environment

In this chapter

• 2.1 Option and Argument Conventions page 24

• 2.2 Basic Command-Line Processing page 28

• 2.3 Option Parsing: getopt() and getopt_long() page 30

• 2.4 The Environment page 40

• 2.5 Summary page 49

• Exercises page 50

Command-line option and argument interpretation is usually the first task of any program. This chapter examines how C (and C++) programs access their command-line arguments, describes standard routines for parsing options, and takes a look at the environment.

Option and Argument Conventions

The word arguments has two meanings. The more technical definition is “all the ’words’ on the command line.” For example:

$ ls main.c opts.c process.c

Here, the user typed four “words.” All four words ...