基础用法详解
（1）第一行之后添加一行
[root@localhost ~]# nl file.txt | sed "1a add text"
1 wtmp begins Mon Feb 24 14:26:08 2014
add text
2 192.168.0.1
3 162.12.0.123
4 this is the last line
(2)第一行之前添加一行
[root@localhost ~]# nl file.txt | sed "1i add text"
add text
1 wtmp begins Mon Feb 24 14:26:08 2014
2 192.168.0.1
3 162.12.0.123
4 this is the last line
（3）删除第2,3行
[root@localhost ~]# nl file.txt | sed "2,3d"
1 wtmp begins Mon Feb 24 14:26:08 2014
4 this is the last line
（4）打印第2,3行
[root@localhost ~]# sed -n "2,3p" file.txt
192.168.0.1
162.12.0.123
这里要提到的是，尽量使用-n，不然会出现这样的结果
[root@localhost ~]# sed "2,3p" file.txt
wtmp begins Mon Feb 24 14:26:08 2014
192.168.0.1
192.168.0.1
162.12.0.123
162.12.0.123
this is the last line
（5）把168换成169
先看源文件
[root@localhost ~]# cat file.txt
wtmp begins Mon Feb 24 14:26:08 2014
192.168.0.1
162.12.0.123
this is the last line
处理后
[root@localhost ~]# sed "s/168/169/g" file.txt
wtmp begins Mon Feb 24 14:26:08 2014
192.169.0.1
162.12.0.123
this is the last line
（6）插入多行
[root@localhost ~]# nl file.txt | sed "2afirst\nsecond" file.txt
wtmp begins Mon Feb 24 14:26:08 2014
192.168.0.1
first
second
162.12.0.123
this is the last line
（7）匹配数据，然后进行操作
只需要在上述的基础上加上正则匹配
sed "/匹配的模式/处理的方式" file.txt
sed "/^root/d" file.txt 对开始有root的删除
例如
匹配begin，并删除改行
[root@localhost ~]# nl file.txt | sed "/begin/d"
2 192.168.0.1
3 162.12.0.123
4 this is the last line
匹配123,并且把含有123的行162都替换成172
[root@localhost ~]# nl file.txt | sed "/123/{s/162/172/g;q}"
1 wtmp begins Mon Feb 24 14:26:08 2014
2 192.168.0.1
3 172.12.0.123
4 this is the last line
这里大括号{}里可以执行多个命令，用;隔开即可,q是退出
（8）连续编辑 -e
删除第二行，并且匹配把last替换成new
1 wtmp begins Mon Feb 24 14:26:08 2014
3 162.12.0.123
4 this is the new line
（9）直接修改文件，切记不要修改系统文件
[root@localhost ~]# sed -i "/begin/{s/24/25/g}" file.txt
[root@localhost ~]# cat file.txt
wtmp begins Mon Feb 25 14:26:08 2014
192.168.0.1
162.12.0.123
this is the last line
一个比较有趣的例子
如何替换\n也就是把所有的行都归为一行
第一种方式
sed ':a;N;$!ba;s/\n/ /g' file.txt
[root@localhost ~]# sed ':a;N;$!ba;s/\n/ /g' file.txt
wtmp begins Mon Feb 25 14:26:08 2014 192.168.0.1 162.12.0.123 this is the last line
第二种方式
tr "\n" " " < file.txt
[root@localhost ~]# tr "\n" " " < file.txt
wtmp begins Mon Feb 25 14:26:08 2014 192.168.0.1 162.12.0.123 this is the last line last linen