sed意为“流编辑器(stream editor)”

字符串筛选工具。

对一个文档中的行进行操作

和vi编辑很相似。可以查看vim使用命令详解

1 sed基本格式

第一种

sed 参数 '脚本语句(/pattern/action)' 待操作文件

第二种

sed 参数 -f '脚本文件' 待操作文件

参数

sed参数

a 追加append

i 插入insert

d 删除delete

s替换substitution

$ cat seqtest

#! /bin/sh

echo "Enter a Yes or no"

read BUF

case "$BUF" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

2 行追加a

追加到后面

$ sed '4a this is an added line' seqtest

执行上面命令后，只会屏幕上输出，而不会保存到文件中

$ sed '4a this is an added line' seqtest

#! /bin/sh

echo "Enter a Yes or no"

read BUF

this is an added line

case "$BUF" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

如果想要保存那就需要加一个参数-i

$ sed -i '4a this is an added line' seqtest

$ cat seqtest

#! /bin/sh

echo "Enter a Yes or no"

read BUF

this is an added line

case "$BUF" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

3 删除某行

$ sed '5d' seqtest

#! /bin/sh

echo "Enter a Yes or no"

read BUF

case "$BUF" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

4 插入某行 和a用法一样，只是追加到行前

5 替换命令s

r$ sed 's/BUF/buffer/g' seqtest

#! /bin/sh

echo "Enter a Yes or no"

read buffer

this is an added line

case "$buffer" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

6常用sed命令

6.1打印包含特定字符的行

相当于grep命令

$ sed -n '/BUF/p' seqtest

read BUF

case "$BUF" in

如果不加-n是下面输出

$ sed '/BUF/p' seqtest

#! /bin/sh

echo "Enter a Yes or no"

read BUF

read BUF

this is an added line

case "$BUF" in

case "$BUF" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

6.2 某字符的特殊模式

$ sed 's/BUF/-$-/g' seqtest

#! /bin/sh

echo "Enter a Yes or no"

read -$-

this is an added line

case "$-$-" in

yes |Y|y|YES|Yes)

echo "It's a yes.";;

[nN]?)

echo "It's a NO.";;

*)

echo "other case.";;

esac

echo "gong to return"

return 0

echo "going to return end"

7 sed扩展sed -r

和grep不同，sed用参数r进行扩展

8 sed一次指定多条不同的替换命令，用";"隔开

9 明白下面例子

$ sed 's/*]>//g' t.html

Hello World

$ sed 's/]*>//g' t.html

Hello World

Welcome to the world of regexp!