7.4. Pattern Matching

The "Hello, world" program does not demonstrate the power of pattern-matching rules. In this section, we look at a number of small, even trivial examples that nonetheless demonstrate this central feature of awk scripts.

When awk reads an input line, it attempts to match each pattern-matching rule in a script. Only the lines matching the particular pattern are the object of an action. If no action is specified, the line that matches the pattern is printed (executing the print statement is the default action). Consider the following script: