输入文件不会被修改，sed 只在模式空间中执行替换命令，然后输出模式空间的
内容。
文本文件 employee.txt
101,John Doe,CEO
102,Jason Smith,IT Manager
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Manager
替换命令用到参数s 注意代码格式
[root@localhost /]# sed ‘s/Manager/Director/‘ employee.txt
101,John Doe,CEO
102,Jason Smith,IT Director
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Director
[root@localhost /]# sed ‘/Sales/s/Manager/Director/‘ employee.txt
101,John Doe,CEO
102,Jason Smith,IT Manager
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Director
用大写 A 替换第一次出现的小写字母 a
[root@localhost /]# sed ‘s/a/A/‘ employee.txt
101,John Doe,CEO
102,JAson Smith,IT Manager
103,RAj Reddy,Sysadmin
104,AnAnd Ram,Developer
105,JAne Miller,Sales Manager
把所有小写字母 a 替换为大写字母 A
[root@localhost /]# sed ‘s/a/A/g‘ employee.txt
101,John Doe,CEO
102,JAson Smith,IT MAnAger
103,RAj Reddy,SysAdmin
104,AnAnd RAm,Developer
105,JAne Miller,SAles MAnAger
把第二次出现的小写字母 a 替换为大写字母 A
[root@localhost /]# sed ‘s/a/A/2‘ employee.txt
101,John Doe,CEO
102,Jason Smith,IT MAnager
103,Raj Reddy,SysAdmin
104,Anand RAm,Developer
105,Jane Miller,SAles Manager
建立一下文件
vi substitute-locate.txt
locate command is used to locate files
locate command uses database to locate files
locate command can also use regex for searching
用刚才建立的文件，把每行中第二次出现的 locate 替换为 find
[root@localhost /]# sed ‘s/locate/find/2‘ substitute-locate.txt
locate command is used to find files
locate command uses database to find files
locate command can also use regex for searching
只打印替换后的行
[root@localhost /]# sed -n ‘s/John/johnny/p‘ employee.txt
101,johnny Doe,CEO
把每行中第二次出现的 locate 替换为 find 并打印出来
[root@localhost /]# sed -n ‘s/locate/find/2p‘ substitute-locate.txt
locate command is used to find files
locate command uses database to find files
标志 w 代表 write，当替换操作执行成功后，它把替换后的结果保存的文件。
把每行出现的 John 替换为 Johnny，只把替换后的内容写到 output.txt 中
[root@localhost /]# sed -n ‘s/John/Johnny/w output.txt‘ employee.txt
[root@localhost /]# cat output.txt
101,Johnny Doe,CEO
把每行第二次出现的 locate 替换为 find，把替换的结果保存到文件中，同时显示输入文件所有内容
[root@localhost /]# sed ‘s/locate/find/2w output.txt‘ substitute-locate.txt
locate command is used to find files
locate command uses database to find files
locate command can also use regex for searching
[root@localhost /]# cat output.txt
locate command is used to find files
locate command uses database to find files
把 john 或 John 替换为 Johnny,但是文件中的John中的J是大写，所以用i参数忽略大小写
[root@localhost /]# sed ‘s/john/Johnny/i‘ employee.txt
101,Johnny Doe,CEO
102,Jason Smith,IT Manager
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Manager
如下图所示，e参数就是执行的作用 文本文件ls -l /etc/passwd e参数则是执行这条命令
[root@localhost /]# vi /files.txt
[root@localhost /]# cat /files.txt
/etc/passwd
/etc/group
[root@localhost /]# sed ‘s/^/ls -l/‘ files.txt
ls -l/etc/passwd
ls -l/etc/group
[root@localhost /]# sed ‘s/^/ls -l /e‘ files.txt
-rw-r--r--. 1 root root 1766 10月 24 15:15 /etc/passwd
-rw-r--r--. 1 root root 920 10月 24 15:15 /etc/group
原文链接：https://blog.csdn.net/weixin_43150761/article/details/83152456
原文：https://www.cnblogs.com/fengfengyang/p/15221361.html