Catalyst 6509 交换机配置手册

格式化输出

[root@localhost ~]# awk -F : 'BEGIN{print "User ID shell"}{printf "%-10s%-10s%-20s\n",$1,$3,$7}' /etc/passwd
User ID shell
root 0 /bin/bash
bin 1 /sbin/nologin
daemon 2 /sbin/nologin
adm 3 /sbin/nologin

将ID小于等于5的输出

[root@localhost ~]# awk -F : '$3<=5{print $1,$3,$7}' /etc/passwd
root 0 /bin/bash
bin 1 /sbin/nologin
daemon 2 /sbin/nologin
adm 3 /sbin/nologin
lp 4 /sbin/nologin
sync 5 /bin/sync

如果字段1是root用户，打印出root用户显示admin。否则打印出用户，显示deamon user

[root@localhost ~]# awk -F : '{if ($1=="root") print $1,"admin" ;else print $1,"deamon user"}' /etc/passwd
root admin
bin deamon user
daemon deamon user
adm deamon user
lp deamon user

格式化输出，如果字段1是root用户，打印出root用户显示admin。否则打印出用户，显示deamon user

[root@localhost ~]# awk -F: '{if($1=="root") printf "%-10s: %s\n",$1,"admin";else printf "%-10s: %s\n",$1,"deamon user"}' /etc/passwd
root : admin
bin : deamon user
daemon : deamon user
adm : deamon user
lp : deamon user

统计ID字段大于等于0的个数（有多少个用户）
[root@localhost ~]# awk -F: -v sum=0 '{if($3>=0) sum++}END{print sum}' /etc/passwd
31

打印出每个字段大于等于4个字符

[root@localhost ~]# awk -F: '{i=1;while(i<=NF){if(length($i)>=4){print $i};i++}}' /etc/passwd
root
root
/root
/bin/bash
/bin
/sbin/nologin

打印出每个字段大于等于4个字符

[root@localhost ~]# awk -F: '{for(i=1;i<=NF;i++){if(length($i)>=4) {print $i}}}' /etc/passwd

统计TCP连接数（以tcp为开头，State[$NF]++定义下标最后字段相加，END最后通过for循环将State下标
遍布给S，打印出下标名称，State[S]下标个数）

[root@localhost ~]# netstat -tnl|awk '/^tcp/{State[$NF]++}END{for(S in State) print S,State[S]}'
LISTEN 6

[root@localhost ~]# netstat -tnl|awk '/^tcp/{State[$NF]++}END{for(i in State) print i,State[i]}'
LISTEN 6

统计IP访问次数
[root@localhost ~]# awk '{count[$1]++}END{for(i in count) {printf "%-20s:%d\n",i,count[i]}}' access.log