一、简介
sed全称是stream editor，是一个用于文本过滤和替换的流编辑器，它是一个管道命令，数据源来自stdin，它的最小处理单位是行（与awk区分）。
二、语法
语法如下：
sed [-nfri] [动作]
-n:使用安静模式。只有经过sed处理的行才会输出到屏幕上
-f:直接将sed的动作写在一个文件内，-f filename 则可以执行filename内的sed动作
-r:切换为支持扩展正则表达式
-i:直接修改读取的文件内容，而不是由屏幕输出
[动作]
[n1[,n2]]function
n1 n2表示应用sed的行数，可以不存在该参数
function参数说明：
a:新增，a的后面可以接字符串，这些字符串会出现在下一行（新行）
c:替换，c的后面可以接字符串，这些字符串将替换n1到n2之间的行
d:删除，删除n1到n2之前的行
i:插入，i的后面可以接字符串，这些字符串会出现在上一行（新行）
p:打印，也就是将某个选择的数据打印出来。通常p会与sed -n一起使用
s:替换，如将1到20行之间的old替换为new：1,20s/old/new/g三、测试文本
测试文本的内容如下所示，创建一个新文件regular_express.txt，并将下面的内容拷贝到文件中即可开始试验：
Football game is not use feet only.
this dress doesn't fit me.
However, this dress is about $ 3183 dollars.^M
GNU is free air not free beer.^M
Her hair is very beauty.^M
I can't finish the test.^M
Oh! The soup taste good.^M
motorcycle is cheap than car.
This window is clear.
the symbol '*' is represented as start.
Oh! My god!
The gd software is a library for drafting programs.^M
You are the best is mean you are the no. 1.
The world <Happy> is the same with "glad".
I like dog.
google is the best tools for search keyword.
goooooogle yes!
go! go! Let's go.
# I am VBird
四、删除实例d
使用sed删除文件的2,5行：
[nigel]$ nl regular_express.txt | sed '2,5d'
1 "Open Source" is a good mechanism to develop programs.
6 GNU is free air not free beer.^M
7 Her hair is very beauty.^M
8 I can't finish the test.^M如果要删除第3行到最后一行，则可以这样：
[nigel@/vbird_linux]$ nl regular_express.txt | sed '3,$d'
1 "Open Source" is a good mechanism to develop programs.
2 apple is my favorite food.只删除第2行：
[nigel@/vbird_linux]$ nl regular_express.txt | sed '2d'
1 "Open Source" is a good mechanism to develop programs.
3 Football game is not use feet only.五、插入实例a，i
[nigel@/vbird_linux]$ nl regular_express.txt | sed '2a Hello world'
1 "Open Source" is a good mechanism to develop programs.
2 apple is my favorite food.
Hello world
3 Football game is not use feet only.
[nigel@/vbird_linux]$ nl regular_express.txt | sed '2i Hello world'
1 "Open Source" is a good mechanism to develop programs.
Hello world
2 apple is my favorite food.
3 Football game is not use feet only.多行的插入比较特殊：
[nigel@/vbird_linux]$ nl regular_express.txt | sed '2i Hello \
> world!'
1 "Open Source" is a good mechanism to develop programs.
Hello
world!
2 apple is my favorite food.
3 Football game is not use feet only.多行插入必须要加上\。
六、整行替换c
动作c可以将n1-n2行替换为指定的字符串：
[nigel/vbird_linux]$ nl regular_express.txt | sed '2,5c Hello world'
1 "Open Source" is a good mechanism to develop programs.
Hello world
6 GNU is free air not free beer.^M注意，是将n1-n2替换为一行，总行数会减少。
七、打印p
我们以前要列出11-20行需要这么做“head -n 20 | tail -n 10”，这样处理很麻烦。有了sed后，就可以简单直接取出那几行：
[nigel@ /vbird_linux]$ nl regular_express.txt | sed -n '11,15p'
11 This window is clear.
12 the symbol '*' is represented as start.
13 Oh! My god!
14 The gd software is a library for drafting programs.^M
15 You are the best is mean you are the no. 1.注意要与-n参数一起使用。
八、部分数据的查找并替换s
用法
sed 's/旧字符串/新字符串/g'使用示例：
[nigel@/vbird_linux]$ nl regular_express.txt | sed 's/apple/APPLE/g'
1 "Open Source" is a good mechanism to develop programs.
2 APPLE is my favorite food.九、直接修改文件
sed除了能从管道后去数据外，还能够直接修改文件！
[nigel@/vbird_linux]$ cat regular_express.txt
"Open Source" is a good mechanism to develop programs.
apple is my favorite food.
Football game is not use feet only.
[nigel@/vbird_linux]$ sed -i '1,2d' regular_express.txt
[nigel@/vbird_linux]$ cat regular_express.txt
Football game is not use feet only.不过该功能需要慎用，一旦修改过后就不能恢复。
PS：本文章内容学习自《鸟哥的linux私房菜 基础学习篇（第三版）》，文章中的所有实例都是亲手操作，保证有效。