[Shell 基础] AWK 命令

1. 正常输出
$ cat /etc/passwd
$ awk '{ print }' /etc/passwd
$ awk '{ print $0 }' /etc/passwd

2. 输出 /etc/passwd 个空行或 test 行
$ awk '{ print "" }' /etc/passwd
$ awk '{ print "test" }' /etc/passwd

3. 输出格式化
$ awk -F ":" '{ print $1 " - " $3 }' /etc/passwd
$ awk -F ":" '{printf "%s - %s \n", $1, $3}' /etc/passwd
$ awk -F : '{printf "%s - %s \n", $1, $3}' /etc/passwd
$ cat /etc/passwd | awk -F : '{printf "%s - %s \n", $1, $3}'
$ awk -F ":" '{ print "username: " $1 "\t\tuid:" $3 }' /etc/passwd

4. Java 输出结果 (print) 经过 AWK 处理后赋值给 shell 变量
#!bin/sh
result=$(/usr/bin/java HelloWorld arg1 $* | awk '{ print $1}')
echo $result # Hello World!