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awk命令(2)
一、awk的正则表达式
1.正则表达式常见的用法
[A-Z]一个大写字母
[a-z]一个小写字母
[0-9]一个数字
[^A-Z]除了大写字母之外的一个字符
[^a-zA-Z]一个非英文字母的字符
[^a-zA-Z0-9]一个非英文字母、且非数字的字符
[a-z]\{3,5\}代表以小写字母组成的字符串，长度是3～5
2.查看tcp端口状态
[root@localhost ~]# netstat -ltn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:2208 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:817 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:2207 0.0.0.0:* LISTEN
tcp 0 0 :::5989 :::* LISTEN
tcp 0 0 :::22 :::* LISTEN
3.截取端口信息
[root@localhost ~]# netstat -ltn |awk ‘{print $4}‘ |awk -F: ‘/[0-9]$/ {print $NF}‘
2208
111
817
631
25
2207
5989
22
4.打印匹配mysql或者oracle的数据
[root@localhost ~]# awk ‘$0~/mysql|oracle/{print $0}‘ /etc/passwd
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
oracle:x:500:501::/home/oracle:/bin/bash
5.打印匹配m或o或r开始的数据
[root@localhost ~]# awk ‘$0~/^[mor]/{print $0}‘ /etc/passwd
root:x:0:0:root:/root:/bin/bash
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
mailnull:x:47:47::/var/spool/mqueue:/sbin/nologin
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
oracle:x:500:501::/home/oracle:/bin/bash
6.打印非字母的数据
[root@localhost ~]# awk ‘{if($0~/^[^a-zA-Z]/) print $0}‘ /etc/passwd
二、awk变量、判断和循环的简单用法
1，定义变量a="name is:",打印变量a和第一列
[root@localhost ~]# awk -F: ‘{a="name is:"} /root/ {print a,$1}‘ /etc/passwd
name is: root
name is: operator
2.begin定义变量，定义变量aa=0,匹配root就加1，完成之后再打印命令aa
[root@localhost ~]# awk ‘BEGIN{aa=0} /root/ {aa++} END{print aa}‘ /etc/passwd
2
3.if判断
[root@localhost ~]# awk -F: ‘{if($7!~"nologin") print $1,$7;else print NR,$NF}‘ /etc/passwd
root /bin/bash
2 /sbin/nologin
sync /bin/sync
shutdown /sbin/shutdown
9 /sbin/nologin
32 /sbin/nologin
mysql /bin/bash
oracle /bin/bash
...
4.循环
if查看有两行
[root@localhost ~]# awk ‘{if($0~/root/) print $0}‘ /etc/passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
while只查询一行就退出
[root@localhost ~]# awk ‘{while ($0~/root/) {print $0;exit}}‘ /etc/passwd
root:x:0:0:root:/root:/bin/bash
三、&&和||
[root@localhost shell]#tail -3 /etc/passwd |awk -F: ‘{if($0 ~ "27" && $0 ~ "bash") print $0 }‘
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
[root@localhost shell]# tail -3 /etc/passwd |awk -F: ‘{if($0 ~ "mysql" || $0 ~ "oracle") print $0 }‘
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
oracle:x:500:501::/home/oracle:/bin/bash
四、awk内置变量
RS：行分隔符
FS：列分隔符
OFS：定义列分隔符
ORS：定义行分隔符，默认是\n转行
FILENAME:文件名
FILENAME的用法
[root@localhost shell]#awk ‘BEGIN {FS="："} {print NF,NR,$NF,$0}END{print "====================================================\n" FILENAME}‘ /etc/passwd
1 1 root:x:0:0:root:/root:/bin/bash root:x:0:0:root:/root:/bin/bash
1 2 bin:x:1:1:bin:/bin:/sbin/nologin bin:x:1:1:bin:/bin:/sbin/nologin
1 3 daemon:x:2:2:daemon:/sbin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin
1 4 adm:x:3:4:adm:/var/adm:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin
....
1 40 oracle:x:500:501::/home/oracle:/bin/bash oracle:x:500:501::/home/oracle:/bin/bash
====================================================
/etc/passwd
五、awk内置的字符串函数
1.gsub(r,s)在整个$0中用s替换r
[root@localhost ~]# awk ‘gsub ("root","bob"){print $0}‘ /etc/passwd
bob:x:0:0:bob:/bob:/bin/bash
operator:x:11:0:operator:/bob:/sbin/nologin
效果等同于sed的全局替换
[root@localhost ~]# sed -n ‘s/root/bob/gp‘ /etc/passwd
bob:x:0:0:bob:/bob:/bin/bash
operator:x:11:0:operator:/bob:/sbin/nologin
gsub(r,s,t)在整个t中用s替换r
[root@localhost ~]# awk ‘gsub ("root","bob",$2){print $0}‘ sedtest.txt
root bob root
root bob root
2.sub(r,s)用$0中最左边最长的子串代替s
[root@localhost ~]# awk ‘sub ("root","bob"){print $0}‘ /etc/passwd
bob:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/bob:/sbin/nologin
效果等同于sed局部替换
[root@localhost ~]# sed -n ‘s/root/bob/p‘ /etc/passwd
bob:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/bob:/sbin/nologin
3.index(s,t)返回s中字符串t的位置
[root@localhost ~]# awk ‘BEGIN{print index("I love you","ov")}‘
4
4.length(s)返回s长度
[root@localhost ~]# awk ‘BEGIN{print length("I love you")}‘
10
5.match(s,r)测试s是否包含匹配r的字符串
[root@localhost ~]# awk ‘BEGIN{print match("I love you","v")}‘
5
[root@localhost ~]# awk ‘BEGIN{print match("I love you","a")}‘
0
6.split(s,a,fs)在fs上将s分成序列a
7.substr(s,p)返回字符串s中从p开始的后缀部分
8.substr(s,p,n)返回字符串s中从p开始长度为n的后缀部分
六、awk内置数学函数
int(x)
sqrt(x)
exp(x)
log(x)
sin(x)
cos(x)
等
本文出自 “卡卡西” 博客，请务必保留此出处http://whnba.blog.51cto.com/1215711/1611014
awk命令(2)