一、簡介

sed全稱是stream editor，是一個用於文字過濾和替換的流編輯器，它是一個管道命令，資料來源來自stdin，它的最小處理單位是行（與awk區分）。

二、語法

語法如下：

sed [-nfri] [動作]
-n:使用安靜模式。只有經過sed處理的行才會輸出到螢幕上
-f:直接將sed的動作寫在一個檔案內，-f filename 則可以執行filename內的sed動作
-r:切換為支援擴充套件正則表示式
-i:直接修改讀取的檔案內容，而不是由螢幕輸出

[動作]
[n1[,n2]]function
n1 n2表示應用sed的行數，可以不存在該引數

function引數說明：
a:新增，a的後面可以接字串，這些字串會出現在下一行（新行）
c:替換，c的後面可以接字串，這些字串將替換n1到n2之間的行
d:刪除，刪除n1到n2之前的行
i:插入，i的後面可以接字串，這些字串會出現在上一行（新行）
p:列印，也就是將某個選擇的資料打印出來。通常p會與sed -n一起使用
s:替換，如將1到20行之間的old替換為new：1,20s/old/new/g
 

三、測試文字

測試文字的內容如下所示，建立一個新檔案regular_express.txt，並將下面的內容拷貝到檔案中即可開始試驗：

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、刪除例項d

使用sed刪除檔案的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

如果要刪除第3行到最後一行，則可以這樣：

[[email protected]/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.

只刪除第2行：

[[email protected]/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、插入例項a，i

[[email protected]/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.

[[email protected]/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.

多行的插入比較特殊：

[[email protected]/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.

多行插入必須要加上\。

六、整行替換c

動作c可以將n1-n2行替換為指定的字串：

[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，是將n1-n2替換為一行，總行數會減少。

七、列印p

我們以前要列出11-20行需要這麼做“head -n 20 | tail -n 10”，這樣處理很麻煩。有了sed後，就可以簡單直接取出那幾行：

[[email protected] /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.

注意要與-n引數一起使用。

八、部分資料的查詢並替換s

用法

sed 's/舊字串/新字串/g'

使用示例：

[[email protected]/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、直接修改檔案

sed除了能從管道後去資料外，還能夠直接修改檔案！

[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.

不過該功能需要慎用，一旦修改過後就不能恢復。

PS：本文章內容學習自《鳥哥的linux私房菜 基礎學習篇（第三版）》，文章中的所有例項都是親手操作，保證有效。