sed
替換
修改第二行的文本
$ sed '2,s/dog/cat' file
修改第二，三行的文本
$ sed '2,3s/dog/cat/' file
修改第二行以後的文本，可以用特殊地址----美元符
$ sed '2,$ s/dog/cat/' file
刪除 d
使用該命令時要特別小心，如果忘記加入尋址模式，流中的所有文本行都會被刪除
刪除第三行
$ sed '3d' file
刪除第二，三行
$ sed '2,3d' file
刪除第三行以後
$ sed '3,$ d' file
$ cat file
This is number 1.
This is number 2.
This is number 3.
This is number 4.
匹配模式也適用於刪除命令,刪除掉匹配指定模式的行
$ sed '/number 1/d' file
This is number 2.
This is number 3.
This is number 4.
也可以使用兩個文本模式來刪除某個區間的行，但是要小心。指定的第一個模式會‘打開’行刪除功能，第二個模式會‘關閉’行刪除功能
$ sed '/1/,/3/d' file
This is number 4.
只要sed在數據流中匹配到了開始模式，刪除功能就會打開，可能會導致意外的結果。
$ cat file
This is number 1.
This is number 2.
This is number 3.
This is number 4.
This is line number 1 again.
This is text you want to keep.
This is the last line in the file
第二個1的行再次觸發了刪除命令。但一直沒有匹配到結束模式，所以整個數據流都被刪除掉了。
$ sed '/1/,/3/d' file
This is line number 4.
插入和附加文本
插入
- i 會在指定行前增加一個新行
- a 會在指定行後增加一個新行
$ echo "Test Line 2" | sed 'i\Test Line1'
Test Line 1
Test Line 2
$ echo "Test Line 2" | sed 'a\Test Line1'
Test Line 2
Test Line 1
$ cat data6.txt
This is line number 1
This is line number 2
This is line number 3
This is line number 4
This is line number 5
This is line number 6
$ sed '3i\This is an inserted line' data6.txt
This is line number 1
This is line number 2
This is an inserted line
This is line number 3
This is line number 4
This is line number 5
This is line number 6
在文件末尾追加數據,用美元符號$
$ sed '$ a\This is a new line of text' data6.txt
This is line number 1
This is line number 2
This is line number 3
This is line number 4
This is line number 5
This is line number 6
This is a new line of text
修改行
- c 修改數據流中整行文本的內容
$ sed '3c\This is a changed line of text' data6.txt
This is line number 1
This is line number 2
This is a changed line of text
This is line number 4
This is line number 5
This is line number 6
$ sed '/number 2/c\This is a changed line of text' data6.txt
This is line number 1
This is a changed line of text
This is line number 3
This is line number 4
This is line number 5
This is line number 6
$ sed '2,3c\This is a changed line of text' data6.txt
This is line number 1
This is a changed line of text
This is line number 4
This is line number 5
This is line number 6
轉換命令
- y 是唯一可以處理單個字符的sed編輯器命令。
- y/inchars/outchars
- 轉換命令會對inchars和outchars值進行一對一映射。
- inchars中的第一個字符轉換爲outchars中的第一個字符
- inchars中的第二個字符圍追爲outchars中的第二個字符
- 如果inchars和outchars的長度不同，sed會產生一條錯誤消息
$ sed 'y/123/789/' data6.txt
This is line number 7
This is line number 8
This is line number 9
This is line number 4
This is line number 5
This is line number 6
使用sed處理文件
- w 向文件寫入行
- r 允許將一個獨立文件中的數據插入到數據流中
- -n 禁止顯示到STDOUT上
向文件行寫入行
$ sed '1,2w text.txt' data6.txt
This is line number 1
This is line number 2
This is line number 3
This is line number 4
This is line number 5
This is line number 6
$ cat text.txt
This is line number 1
This is line number 2
$ cat data11.txt
Blum, R Browncoat
McGuiness, A Alliance
Bresnahan, C Browncoat
Harken, C Alliance
$ sed -n '/Browncoat/w Browncoat.txt' data11.txt
$ cat Browncoat.txt
Blum, R Browncoat
Bresnahan, C Browncoat
從文件讀取數據
讀取命令中使用地址區間，只能指定單獨一個行號或文本模式地址。sed會將文本中的文本插入到指定地址後。
$ cat data12.txt
This is an added line.
This is the second added line.
$ sed '3r data12.txt' data6.txt
This is line number 1
This is line number 2
This is line number 3
This is an added line.
This is the second added line.
This is line number 4
This is line number 5
This is line number 6
$ sed '/number 2/r data12.txt' data6.txt
This is line number 1
This is line number 2
This is an added line.
This is the second added line.
This is line number 3
This is line number 4
This is line number 5
This is line number 6
$ cat notice.std
Would the following people:
LIST
please report to the ship's caption
$ sed '/LIST/{
> r data11.txt
> }' notice.std
Would the following people:
LIST
Blum, R Browncoat
McGuiness, A Alliance
Bresnahan, C Browncoat
Harken, C Alliance
please report to the ship's caption
刪除佔位文本，使用刪除命令 d
$ sed '/LIST/{
> r data11.txt
> d
> }' notice.std
Would the following people:
Blum, R Browncoat
McGuiness, A Alliance
Bresnahan, C Browncoat
Harken, C Alliance
please report to the ship's caption