sed命令
一、替换标记
s/pattern/replacement/flags
默认情况下只会替换每行的首次出现的内容，如果要替换其他位置需要使用flags
1、不使用flag
[root@bogon tmp]# cat data.txt
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
[root@bogon tmp]# sed 's/test/aaa/' data.txt
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
[root@bogon tmp]# cat data.txt
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
2、使用flags/pattern/replacement/flags
有4种可用的替换标记：
- 数字，表明新文本将替换第几处模式匹配的地方；
- g，表明新文本将会替换所有匹配的文本；
- p，表明原先行的内容要打印出来；
- w file，将替换的结果写到文件中。
1）数字型，比如数字2，替换第2次出现的内容，不会修改原文件
[root@bogon tmp]# sed 's/test/hhhh/2' data.txt
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
this is a test of the hhhh script.
2）g，替换所有的行，不会修改原文件
[root@bogon tmp]# sed 's/test/aaa/g' data.txt
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
this is a aaa of the aaa script.
3）w file，将替换的结果写到新文件中，不会替换原文件
[root@bogon tmp]# sed 's/test/aaa/w aaa.txt' data.txt
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
this is a aaa of the test script.
查看当前目录，多了文件aaa.txt
[root@bogon tmp]# ls
aaa.txt keyring-nBhNRc orbit-gdm pulse-PDnM11f40MzK VMwareDnD
data.txt keyring-o1ipCa orbit-root pulse-tvQCaCozIrxH
4）p，p替换标记会打印与替换命令中指定的模式匹配的行
[root@bogon tmp]# cat aaa.txt
this is a aaa of the test script.
this is a sss of the test script.
[root@bogon tmp]# sed 's/aaa/test/p' aaa.txt
this is a test of the test script.
this is a test of the test script.
this is a sss of the test script.
这通常会和sed的-n选项一起使用。
$ cat data5.txt
This is a test line.
This is a different line.
$ sed -n 's/test/trial/p' data5.txt
This is a trial line.
-n选项将禁止sed编辑器输出。但p替换标记会输出修改过的行。将二者配合使用的效果就是
只输出被替换命令修改过的行。
二、使用地址
默认情况下，sed命令作用于文本数据的所有行。如果只想将命令作用于特定行或者某些行，则需要使用行寻址。
sed编辑器的2种行寻址方式：
- 以数字形式表示行区间
- 用文本模式来过滤出行
[address] command
address {
command1
command2
command3
}
1、数字方式行寻址
[root@localhost tmp]# sed '2s/test/hhh/' aaa.txt
this is a aaa of the test script.
this is a sss of the hhh script.
修改2-4行每行第2次匹配上的内容
[root@localhost tmp]# sed '2,4s/test/hhh/2' data.txt
this is a test of the test script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
修改第2行至最后一行的匹配的内容
[root@localhost tmp]# sed '2,$s/test/hhh/2' data.txt
this is a test of the test script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
this is a test of the hhh script.
2、命令组合方式
[root@localhost ~]# sed '2,4{ 修改2-4行的内容
> s/test/hhh/2 修改每行的第2次匹配的内容
> s/a test/1111/ 修改每行的第1次匹配的内容
> }' /tmp/data.txt
this is a test of the test script.
this is 1111 of the hhh script.
this is 1111 of the hhh script.
this is 1111 of the hhh script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
this is a test of the test script.
[root@localhost ~]#
3、删除行
$ sed '/number 1/d' data6.txt
This is line number 2.
This is line number 3.
This is line number 4.