sed Shell 文字處理利器

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

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的動作寫在乙個檔案內，-f filename 則可以執行filename內的sed動作 -r:切換為支援擴充套件正規表示式 -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列印出來。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

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

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 same with

"glad".

i like dog.

google is

the best tools for search keyword.

goooooogle yes!

go! go! let's go.

# i am vbird

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：

[nigel@/vbird_linux]$ nl regular_express.txt | sed '3,$d'
1"open source"
is a good mechanism to develop programs.

只刪除第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.

[nigel@/vbird_linux]$ nl regular_express.txt | sed '2a hello world' 1"open source" is a good mechanism to develop programs. 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 3 football game is

not use feet only.

多行的插入比較特殊：

[nigel@/vbird_linux]$ nl regular_express.txt | sed '2i hello \ > world!' 1"open source" is a good mechanism to develop programs. hello world! 3 football game is

not use feet only.

多行插入必須要加上\。

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。

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：

[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.

注意要與-n引數一起使用。

用法

sed 's/舊字串/新字串/g'

使用示例：

1"open source"

is a good mechanism to develop programs.

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. 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。

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