下面这些命令未必经常会用到，但当需要时，知道这些肯定是件好事。
sed命令通常是对一行数据进行处理，然后下一行重复处理。
sed编辑器包含了三个可用来处理多行文本的特殊命令
两种删除匹配的下一行的办法：
cat data1.txt This is the header line. This is a data line. This is the last line. sed ‘/^$/d‘ data1.txt This is the header line. This is a data line. This is the last line. sed ‘/header/{n ; d}‘ data1.txt This is the header line. This is a data line. This is the last line.
用大写N，可以一次性读取两行。区别与n是移动到下一行。
$ sed ‘/first/{ N ; s/\n/ / }‘ data2.txt This is the header line. This is the first data line. This is the second data line. This is the last line. $ cat data2.txt This is the header line. This is the first data line. This is the second data line. This is the last line. $ cat data3.txt On Tuesday, the Linux System Administrator‘s group meeting will be held. All System Administrators should attend. Thank you for your attendance. $ sed ‘N ; s/System.Administrator/Desktop User/‘ data3.txt On Tuesday, the Linux Desktop User‘s group meeting will be held. All Desktop Users should attend. Thank you for your attendance.
在N后面最好匹配多行命令，而单行命令则可以放在N前面，如：
$ sed ‘N > s/System\nAdministrator/Desktop\nUser/ > s/System Administrator/Desktop User/ > ‘ data4.txt On Tuesday, the Linux Desktop User‘s group meeting will be held. All System Administrators should attend. $ cat data4.txt On Tuesday, the Linux System Administrator‘s group meeting will be held. All System Administrators should attend. $ sed ‘ > s/System Administrator/Desktop User/ > N > s/System\nAdministrator/Desktop\nUser/ > ‘ data4.txt On Tuesday, the Linux Desktop User‘s group meeting will be held. All Desktop Users should attend.
二、保持空间
三、排除命令
四、改变流
五、模式替代
六、在脚本中使用sed
七、创建sed实用工具
原文：https://www.cnblogs.com/ch122633/p/10311935.html
