Shell三剑客：awk（模式（正则表达式）和动作）

一、运算符

二、示例

#过滤第一列大于2的行
[root@localhost ~]# awk '$1>2' log.txt 
3 Are you like awk
This's a test
10 There are orange,apple,mongo

#过滤第一列等于2的行
[root@localhost ~]# awk '$1==2 {print $1,$3}' log.txt 
2 is

#过滤第一列大于2并且第二列等于'Are'的行
[root@localhost ~]# awk '$1>2 && $2=="Are" {print $1,$2,$3}' log.txt 
3 Are you


[root@localhost ~]# awk -F: '$3 == 0' passwd.txt 
root:x:0:0:root:/root:/bin/bash

[root@localhost ~]# awk -F: '$3 < 10' passwd.txt 
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin

[root@localhost ~]# awk -F: '$3 < 5' passwd.txt 
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

[root@localhost ~]# awk -F: '$NF == "/bin/bash"' passwd.txt 
root:x:0:0:root:/root:/bin/bash

[root@localhost ~]# awk -F: '$1 == "root"' passwd.txt 
root:x:0:0:root:/root:/bin/bash

[root@localhost ~]# awk -F: '$1 ~ /roo/' passwd.txt 
root:x:0:0:root:/root:/bin/bash

[root@localhost ~]# awk -F: '$1 !~ /roo/' passwd.txt 
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin10

[root@localhost ~]# df -P | grep '/' | awk '$4 > 25000'
devtmpfs                 485816       0  485816   0% /dev
tmpfs                    497836       0  497836   0% /dev/shm
tmpfs                    497836   13968  483868   3% /run
tmpfs                    497836       0  497836   0% /sys/fs/cgroup
/dev/mapper/centos-root 6486016 1898056 4587960  30% /
/dev/sda1               1038336  140336  898000  14% /boot
tmpfs                     99568       0   99568   0% /run/user/0