awk 流程控制语句实例
一、匹配代码块
匹配模式如下：
1//纯字符匹配
2!//纯字符不匹配
3~//字段值匹配
4!~//字段值不匹配
5~/a1|a2/字段值匹配a1或a2
示例如下：
1awk '/mysql/' /etc/passwd
2awk '/mysql/{print }' /etc/passwd
3awk '/mysql/{print $0}' /etc/passwd //三条指令结果一样
4awk '!/mysql/{print $0}' /etc/passwd //输出不匹配mysql的行
5awk '/mysql|mail/{print}' /etc/passwd
6awk '!/mysql|mail/{print}' /etc/passwd
7awk -F: '/mail/,/mysql/{print}' /etc/passwd //区间匹配
8awk '/[2][7][7]*/{print $0}' /etc/passwd //匹配包含27为数字开头的行，如27，277，2777...
9awk -F: '$1~/mail/{print $1}' /etc/passwd //$1匹配指定内容才显示
10awk -F: '{if($1~/mail/) print $1}' /etc/passwd //与上面相同
11awk -F: '$1!~/mail/{print $1}' /etc/passwd //不匹配
12awk -F: '$1!~/mail|mysql/{print $1}' /etc/passwd
二、IF语句
必须用在{}中，且比较内容用()扩起来
1awk -F: '{if($1~/mail/) print $1}' /etc/passwd //简写
2awk -F: '{if($1~/mail/) {print $1}}' /etc/passwd //全写
3awk -F: '{if($1~/mail/) {print $1} else {print $2}}' /etc/passwd //if...else...
三、条件表达式
表达式：
1== != > >=
示例：
1awk -F":" '$1=="mysql"{print $3}' /etc/passwd
2awk -F":" '{if($1=="mysql") print $3}' /etc/passwd //与上面相同
3awk -F":" '$1!="mysql"{print $3}' /etc/passwd //不等于
4awk -F":" '$3>1000{print $3}' /etc/passwd //大于
5awk -F":" '$3>=100{print $3}' /etc/passwd //大于等于
6awk -F":" '$3<1{print $3}' /etc/passwd //小于
7awk -F":" '$3<=1{print $3}' /etc/passwd //小于等于
四、逻辑运算符
表达式：
1&& ||
示例
1awk -F: '$1~/mail/ && $3>8 {print }' /etc/passwd //逻辑与，$1匹配mail，并且$3>8
2awk -F: '{if($1~/mail/ && $3>8) print }' /etc/passwd
3awk -F: '$1~/mail/ || $3>1000 {print }' /etc/passwd //逻辑或
4awk -F: '{if($1~/mail/ || $3>1000) print }' /etc/passwd
五、数值运算
1awk -F: '$3 > 100' /etc/passwd
2awk -F: '$3 > 100 || $3 < 5' /etc/passwd
3awk -F: '$3+$4 > 200' /etc/passwd
4awk -F: '/mysql|mail/{print $3+10}' /etc/passwd //第三个字段加10打印
5awk -F: '/mysql/{print $3-$4}' /etc/passwd //减法
6awk -F: '/mysql/{print $3*$4}' /etc/passwd //求乘积
7awk '/MemFree/{print $2/1024}' /proc/meminfo //除法
8awk '/MemFree/{print int($2/1024)}' /proc/meminfo //取整
六、输出分隔符OFS
1awk '$6 ~ /FIN/ || NR==1 {print NR,$4,$5,$6}' OFS="\t" netstat.txt
2awk '$6 ~ /WAIT/ || NR==1 {print NR,$4,$5,$6}' OFS="\t" netstat.txt
3//输出字段6匹配WAIT的行，其中输出每行行号，字段4，5,6，并使用制表符分割字段
七、输出处理结果到文件
1①在命令代码块中直接输出 route -n|awk 'NR!=1{print > "./fs"}'
2②使用重定向进行输出 route -n|awk 'NR!=1{print}' > ./fs
八、格式化输出
1netstat -anp|awk '{printf "%-8s %-8s %-10s\n",$1,$2,$3}'
printf表示格式输出
- %格式化输出分隔符
- -8长度为8个字符
- s表示字符串类型
打印每行前三个字段，指定第一个字段输出字符串类型(长度为8)，第二个字段输出字符串类型(长度为8),
第三个字段输出字符串类型(长度为10)
1netstat -anp|awk '$6=="LISTEN" || NR==1 {printf "%-10s %-10s %-10s \n",$1,$2,$3}'
2netstat -anp|awk '$6=="LISTEN" || NR==1 {printf "%-3s %-10s %-10s %-10s \n",NR,$1,$2,$3}'
IF语句
1awk -F: '{if($3>100) print "large"; else print "small"}' /etc/passwd
2small
3small
4small
5large
6small
7small
8awk -F: 'BEGIN{A=0;B=0} {if($3>100) {A++; print "large"} else {B++; print "small"}} END{print A,"\t",B}' /etc/passwd
9
10//ID大于100,A加1，否则B加1
11awk -F: '{if($3<100) next; else print}' /etc/passwd //小于100跳过，否则显示
12awk -F: 'BEGIN{i=1} {if(i<NF) print NR,NF,i++ }' /etc/passwd
13awk -F: 'BEGIN{i=1} {if(i<NF) {print NR,NF} i++ }' /etc/passwd
14另一种形式
15awk -F: '{print ($3>100 ? "yes":"no")}' /etc/passwd
16awk -F: '{print ($3>100 ? $3":\tyes":$3":\tno")}' /etc/passwd
while语句
1awk -F: 'BEGIN{i=1} {while(i<NF) print NF,$i,i++}' /etc/passwd
27 root 1
37 x 2
47 0 3
57 0 4
67 root 5
77 /root 6
数组
1netstat -anp|awk 'NR!=1{a[$6]++} END{for (i in a) print i,"\t",a[i]}'
2netstat -anp|awk 'NR!=1{a[$6]++} END{for (i in a) printf "%-20s %-10s %-5s \n", i,"\t",a[i]}'
39523 1
49929 1
5LISTEN 6
67903 1
73038/cupsd 1
87913 1
910837 1
109833 1
应用1
1awk -F: '{print NF}' helloworld.sh //输出文件每行有多少字段
2awk -F: '{print $1,$2,$3,$4,$5}' helloworld.sh //输出前5个字段
3awk -F: '{print $1,$2,$3,$4,$5}' OFS='\t' helloworld.sh //输出前5个字段并使用制表符分隔输出
4awk -F: '{print NR,$1,$2,$3,$4,$5}' OFS='\t' helloworld.sh //制表符分隔输出前5个字段，并打印行号
应用2
1awk -F'[:#]' '{print NF}' helloworld.sh //指定多个分隔符: #，输出每行多少字段
2awk -F'[:#]' '{print $1,$2,$3,$4,$5,$6,$7}' OFS='\t' helloworld.sh //制表符分隔输出多字段
应用3
1awk -F'[:#/]' '{print NF}' helloworld.sh //指定三个分隔符，并输出每行字段数
2awk -F'[:#/]' '{print $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12}' helloworld.sh //制表符分隔输出多字段
应用4
计算/home目录下，普通文件的大小，使用KB作为单位
1ls -l|awk 'BEGIN{sum=0} !/^d/{sum+=$5} END{print "total size is:",sum/1024,"KB"}'
2ls -l|awk 'BEGIN{sum=0} !/^d/{sum+=$5} END{print "total size is:",int(sum/1024),"KB"}' //int是取整的意思
应用5
统计netstat -anp 状态为LISTEN和CONNECT的连接数量分别是多少
1netstat -anp|awk '$6~/LISTEN|CONNECTED/{sum[$6]++} END{for (i in sum) printf "%-10s %-6s %-3s \n", i," ",sum[i]}'
应用6
统计/home目录下不同用户的普通文件的总数是多少？
1ls -l|awk 'NR!=1 && !/^d/{sum[$3]++} END{for (i in sum) printf "%-6s %-5s %-3s \n",i," ",sum[i]}'
2mysql 199
3root 374
统计/home目录下不同用户的普通文件的大小总size是多少？
1ls -l|awk 'NR!=1 && !/^d/{sum[$3]+=$5} END{for (i in sum) printf "%-6s %-5s %-3s %-2s \n",i," ",sum[i]/1024/1024,"MB"}'
应用7
输出成绩表
1awk 'BEGIN{math=0;eng=0;com=0;printf "Lineno. Name No.
2 Math English Computer Total\n";printf
3"------------------------------------------------------------\n"}{math+=$3;
4 eng+=$4; com+=$5;printf "%-8s %-7s %-7s %-7s %-9s %-10s %-7s
5\n",NR,$1,$2,$3,$4,$5,$3+$4+$5} END{printf
6"------------------------------------------------------------\n";printf
7"%-24s %-7s %-9s %-20s \n","Total:",math,eng,com;printf "%-24s %-7s %-9s
8 %-20s \n","Avg:",math/NR,eng/NR,com/NR}' test0
9
10[root@localhost home]# cat test0
11Marry 2143 78 84 77
12Jack 2321 66 78 45
13Tom 2122 48 77 71
14Mike 2537 87 97 95
15Bob 2415 40 57 62
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- Author: shisekong
- Link: https://blog.361way.com/awk-crontol/5155.html
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