UNIX® Shells by Example, Third Edition

5.1. What Is awk?

Awk is a programming language used for manipulating data and generating reports. The data may come from standard input, one or more files, or as output from a process. Awk can be used at the command line for simple operations, or it can be written into programs for larger applications. Because awk can manipulate data, it is an indispensable tool used in shell scripts and for managing small databases.

Awk scans a file (or input) line by line, from the first to the last line, searching for lines that match a specified pattern and performing selected actions (enclosed in curly braces) on those lines. If there is a pattern with no specific action, all lines that match the pattern are displayed; if there is an action with no pattern, ...