Learning Linux Shell Scripting - Second Edition

Patterns

awk uses patterns to control the processing of actions. When a pattern or regular expression is found in the record, an action is performed, or if no action is defined then awk simply prints the line on the screen.

This is an example:

    $ cat people.txt
  

The output will be:

    Bill Thomas  8000  08/9/1968
    Fred Martin  6500  22/7/1982
    Julie Moore  4500  25/2/1978
    Marie Jones  6000  05/8/1972
    Tom Walker   7000  14/1/1977
    $ awk '/Bill/' people.txt
  

The output will be:

    Bill Thomas  8000  08/9/1968
  

In this example, when the Bill pattern is found in the record, that record is printed on screen:

    $ awk '$3 > 5000' people.txt
  

The output will be:

    Bill Thomas  8000  08/9/1968
    Fred Martin  6500  22/7/1982
    Marie Jones  6000  05/8/1972
    Tom Walker 7000 14/1/1977 ...