shell 常用命令之四 sed

sed 可以 对文本文件和标准输入进行编辑(键盘输入、文件重定向、字符串、变量、管道文本)。

sed [选项] ‘sed 命令’ 输入文件 //sed对输入文件进行处理

| sed [选项] ‘sed 命令’ //加一个管道，说明sed处理的是从管道中读取的数据，就没必要加 输入文件

当然也可以 cat /etc/passwd | sed -n '/root/p' //显示以root关键字 开头的行

值得注意的是：sed只是对缓冲区中原始文件的的副本进行编辑，并不编辑原始的文件

命令格式：

一、选项

-n:不打印所有的行到标准输出

-e：表示键下一个字符串解释为sed 编辑命令

-f：表示正在调用sed文本

-i :表示在原文本中修改

二、sed命令定位文本的方法

x ：x为指定行号

x,y :指定从x到y的行号范围

x,y！ :查询不包括从x到y的行号范围

/pattern/ :查询包含模式的行
/pattern/pattern/ ：查询包含两个模式的行 //注意：模式间的分隔符不是写死的，可以随意改动，只要三个统一就可以

/pattern/，x ：从与模式匹配的行到x行号之间的行

x，/pattern/ ：从第x行到与pattern相匹配的行之间的行

三、sed编辑命令

p ：打印匹配的行

= ：打印文件的行号

a\ :在定位行号之后追加文本信息

i\ :在定位行号之前追加文本信息

d ：删除定位行

c\ ：用新的文本定位文本

s ：使用替换模式替换相应的模式

r ：从另一个文本中读文本

w ：将文本写入到一个文件

y ：变换字符

四、举例

 [root@zhangna ~]# cat input
This is a Certificate Request file:

It should be mailed to na.zhang@i-soft.com.cn

==================================================================================
Certificate Subject:

/O=Grid/OU=GLOBUSTest/OU=simpleCA-seugridl.seu.edu.cn/OU=seu.edu.cn/CN=globus

The above string is konwn as your user certificate subject,and it uniquely identifies this user .$88
To install this user certificate ,please save this e-mail message into the following file.

/home/globus/.globus/usercert.pem

[root@zhangna ~]# sed '1p' input                                 //没有选项-n,结果：将第一行打印出来之后，会将整个文本打印出来
This is a Certificate Request file:
This is a Certificate Request file:

It should be mailed to na.zhang@i-soft.com.cn

==================================================================================
Certificate Subject:

/O=Grid/OU=GLOBUSTest/OU=simpleCA-seugridl.seu.edu.cn/OU=seu.edu.cn/CN=globus

The above string is konwn as your user certificate subject,and it uniquely identifies this user .$88
To install this user certificate ,please save this e-mail message into the following file.

/home/globus/.globus/usercert.pem

[root@zhangna ~]# sed '3p' input
This is a Certificate Request file:

It should be mailed to na.zhang@i-soft.com.cn
It should be mailed to na.zhang@i-soft.com.cn

==================================================================================
Certificate Subject:

/O=Grid/OU=GLOBUSTest/OU=simpleCA-seugridl.seu.edu.cn/OU=seu.edu.cn/CN=globus

The above string is konwn as your user certificate subject,and it uniquely identifies this user .$88
To install this user certificate ,please save this e-mail message into the following file.

/home/globus/.globus/usercert.pem

[root@zhangna ~]# sed -n '3p' input                                       //加上选项-n,只打印选中的行
It should be mailed to na.zhang@i-soft.com.cn
[root@zhangna ~]# sed -n '3,6p' input                                     //打印3～6行
It should be mailed to na.zhang@i-soft.com.cn

==================================================================================
Certificate Subject:
[root@zhangna ~]# sed -n '/certificate/p' input                          //打印与/certificate/匹配的行
The above string is konwn as your user certificate subject,and it uniquely identifies this user .$88
To install this user certificate ,please save this e-mail message into the following file.
[root@zhangna ~]# sed -n '/Certificate/=' input
1
6
[root@zhangna ~]# sed -n -e '/Certificate/=' -e '/Certificate/p' input               //只有向sed命令传递多个编辑命令时用-e才有意义  ；；；；这是前两个命令汇在了一起
1
    This is a Certificate Request file:
6
    Certificate Subject:
[root@zhangna ~]#
[root@zhangna ~]# sed '/file:/a\this is a new add.' input                                //  a\表示追加到匹配行后
    This is a Certificate Request file:
this is a new add.

    It should be mailed to na.zhang@i-soft.com.cn

    ==================================================================================
    Certificate Subject:

        /O=Grid/OU=GLOBUSTest/OU=simpleCA-seugridl.seu.edu.cn/OU=seu.edu.cn/CN=globus
    
    The above string is konwn as your user certificate subject,and it uniquely identifies this user .$88
    To install this user certificate ,please save this e-mail message into the following file.

    /home/globus/.globus/usercert.pem

下面看一下参数-f 怎么使用
<pre name="code" class="objc">[root@zhangna ~]# cat append.sed                       
#!/bin/sed -f
/file:/a\
We append a new line.\
So we are very happy.
[root@zhangna ~]# ./append.sed input
This is a Certificate Request file:
We append a new line.
So we are very happy.

It should be mailed to na.zhang@i-soft.com.cn

==================================================================================
Certificate Subject:

/O=Grid/OU=GLOBUSTest/OU=simpleCA-seugridl.seu.edu.cn/OU=seu.edu.cn/CN=globus

The above string is konwn as your user certificate subject,and it uniquely identifies this user .$88
To install this user certificate ,please save this e-mail message into the following file.

/home/globus/.globus/usercert.pem

在这在简单说一下-i的用法：sed -i 指定行号 /s被替换模式/替换成模式/ 文件；当然模式间的分隔符可以随便修改，只要三个一样就行。

因此，还有一个表达形式：sed -i "行号"“s@”“str1”“@str2@” 文件 //注意： 黄色部分之间没有空格

例子不在一一在写，自己写个小程序练一下就Ok。