AWK Learning Notes

What is awk?

An awk program is a sequence of patterns and actions that tell what to look for in the input data and what to do when it’s found.

Patterns

Summary of Patterns

String-Matching Patterns

Regular Expression

转义序列

模式总结

Actions

statements in actions

注意：for (expression in array) statements 中的expression是array的index而不是array的element

built-in variables

expressions

built-in arithmetic functions

built-in string functions

expression operators

control-flow statements

用户自定义函数

function name(parameter-list) {
  	statements
  	return result
}

getline函数

注：getline < file和getline var < file可以用在BEGIN中进行“预处理”（不会设置NR变量）。