常用命令-awk

awk是Linux处理文本的利器，在linux日常处理中，发挥很重要的作用，学会使用awk可以让你的处理文本工作事半功倍。此处记录下，awk常用的处理文本方法。

基本用法

#action中要输出字符串需用双引号`"`括起来。
1. `awk '{[pattern] action}' {filename}`
2. `awk -F fs '{action}' {filename}`

常用参数

内建常用变量

运算符

BEGIN/END块

BEGIN{开始处理前执行的语句}
{每行执行的语句}
END{处理完所有行之后执行的语句}

使用示例

~$ cat test.txt
1 my name is kl
2 I'm a software developer
3 I'm so hungry
4 I don't have money,house,girlfiend

# 使用默认分隔符分隔
~$ awk '{print $1,$4}' test.txt
1 is
2 software
3 hungry
4 have

# 使用指定分隔符分隔
~$ awk -F, '{print $1,$2}' test.txt
1 my name is kl
2 I'm a software developer
3 I'm so hungry
4 I don't have money house

# 使用比较运算符
~$ awk '{if($1>2) print $0}' test.txt
3 I'm so hungry
4 I don't have money,house,girlfiend

# 同上
~$ awk '$1>2 {print $0}' test.txt
3 I'm so hungry
4 I don't have money,house,girlfiend

# 使用逻辑与
~$ awk '$1>2 && $2=="I" {print $0}' test.txt
4 I don't have money,house,girlfiend

# 使用正则，打印第二列包含I的行
~$ awk '$2 ~ /I/ {print $0}' test.txt
2 I'm a software developer
3 I'm so hungry
4 I don't have money,house,girlfiend

# 同上
awk '{if($2 ~ /I/)print $0}' test.txt
2 I'm a software developer
3 I'm so hungry
4 I don't have money,house,girlfiend

# 使用变量
~$ awk '{print NR, $0}' test.txt
1 1 my name is kl
2 2 I'm a software developer
3 3 I'm so hungry
4 4 I don't have money,house,girlfiend

# 使用BEGIN/END，对第一列求和
~$ awk 'BEGIN{sum=0} {sum+=$1} END{print "sum is " sum }' test.txt
sum is 10

# 改变第1列的值
~$ awk '{$1++ ;print $0}' test.txt
2 my name is kl
3 I'm a software developer
4 I'm so hungry
5 I don't have money,house,girlfiend