awk是文本处理工具，功能小结如下：
1、条件表达式
[root@centos17 shell]# awk -F: '$3>1&&$3<3{print $0}' /etc/passwd
daemon:x:2:2:daemon:/sbin:/sbin/nologin
[root@centos17 shell]# awk -F: '{if($3>1&&$3<3){print $0}}' /etc/passwd
daemon:x:2:2:daemon:/sbin:/sbin/nologin
[root@centos17 shell]# awk -F: '{if($3>1&&$3<3)print $0}' /etc/passwd
daemon:x:2:2:daemon:/sbin:/sbin/nologin
[root@centos17 shell]#
2、算术运算+ - * / % (模) ^（幂2^3）
可以在模式中执行计算，awk都将按浮点数方式执行算术运算
[root@centos17 shell]# awk -F: '$3*5 > 10000' /etc/passwd
nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin
[root@centos17 shell]# awk -F: '{if($3*5>10000){print $0}}' /etc/passwd
nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin
3、逻辑操作符和复合模式
&& 逻辑与 a&&b
|| 逻辑或 a||b
! 逻辑非 !a
[root@centos17 ~]# awk -F: '$1~/root/&&$3<=2' /etc/passwd #root:x:0:0:root:/root:/usr/sbin/poweroff root:x:0:0:root:/root:/bin/bash [root@centos17 ~]# awk -F: '$1~/root/||$3<=1' /etc/passwd #root:x:0:0:root:/root:/usr/sbin/poweroff root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin [root@centos17 ~]# awk -F: '!($1~/root/||$3>=2)' /etc/passwd bin:x:1:1:bin:/bin:/sbin/nologin [root@centos17 ~]#
4、范围模式
[root@centos17 ~]# awk '/sshd/,/feng/' /etc/passwd sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin chrony:x:997:995::/var/lib/chrony:/sbin/nologin nginx:x:996:992:nginx user:/var/cache/nginx:/sbin/nologin feng:x:1000:1000::/home/feng:/sbin/poweroff [root@centos17 ~]#
5、正则表达式
awk '/^alice/' /etc/passwd awk '$0~/^alice/' /etc/passwd awk '!/alice/' /etc/passwd awk -F: '$NF~/bash$/' /etc/passwd awk -F: '$1~/^alice/' /etc/passwd
6、关系运算符
运算符 含义 示例
< 小于 x<y
<= 小于或等于 x<=y
== 等于 x==y
!= 不等于 x!=y
>= 大于或等于 x>=y
> 大于 x>y
awk -F: '$3==0' /etc/passwd awk -F: '$3<10' /etc/passwd awk -F: '$7=="/bin/bash"' /etc/passwd awk -F: '$1!~/alice/' /etc/passwd
awk示例：
awk '/west/' datafile
awk '/^north/' datafile
awk '$3~/^north/' datafile
awk '/^(no|so)/' datafile
awk '{print $3,$2}' datafile
awk '{print $3 $2}' datafile
awk '{print $0}' datafile
awk '/north/{print $3,$2}' datafile
awk '/E/' datafile
awk '/^[ns]/{print $1}' datafile
awk '$5~/.[7-9]+/' datafile
awk '$2!~/E/{print $1,$2}' datafile
awk '$3~/^joel/{print $3" is a nice boy."}' datafile
awk '$8~/[0-9][0-9]$/{print $8}' datafile
awk '$4~/Chin$/{print "The price is $"$8"."}' datafile
awk '/Tj/{print $0}' datafile
awk -F"[ :]" '{print $0}' datafile
awk -F"[ :]+" '{print $0}' datafile
awk '$7==5' datafile
awk '$7!=5' datafile
awk '$3=="CT"{print $1,$2}' datafile
awk -F: '$2~/nest/{print $3+50}' datafile
awk -F: '$3~/rpc$/{$1="laowang";print $0}' datafile