linux中sed跳转到标签,Linux基础知识：sed命令

在例5中&＃xff0c;每一行都被打印了2次&＃xff0c;原因是在模式空间的时候被打印了一次&＃xff0c;然后处理完成之后&＃xff0c;在标准输出又被打印了一次&＃xff0c;所以自然会显示出两次。如果使用-n,则仅仅打印的模式空间的内容。

a test&＃xff1a;在行后面追加文本"test"&＃xff0c;可以使用\n实现多行追加

[root&＃64;localhost ~]# sed &＃39;1 a hi i am here\nhey&＃39;poetry1)Never give up,

hi i am here

hey2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

i test&＃xff1a;在 行前面插入文本test&＃xff0c;支持使用\n实现多行插入

[root&＃64;localhost ~]# sed &＃39;2i hi i am here\nhey&＃39;poetry1)Never give up,

hi i am here

hey2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

c test&＃xff1a;把匹配到的行替换为此处指定的行

[root&＃64;localhost ~]# sed &＃39;2c hi i am here&＃39;poetry1)Never give up,

hi i am here3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

w /path/to/somefile&＃xff1a;保存模式空间中匹配到的内容到指定的文件中

[root&＃64;localhost ~]# sed &＃39;/So/ w /tmp/poetry&＃39;poetry1)Never give up,2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

[root&＃64;localhost~]#

[root&＃64;localhost~]# cat /tmp/poetry9)So put on a smile,

r /path/from/somefile&＃xff1a;读取指定文件的内容至当前文件中被模式匹配的行后面

[root&＃64;localhost ~]# catpoetry2.txt13)yes! I can![root&＃64;localhost~]# sed &＃39;12 r poetry2.txt&＃39;poetry1)Never give up,2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain13)yes! I can!

&＃61;&＃xff1a;为模式匹配到的行打印行号&＃xff0c;打印在行的上面

[root&＃64;localhost ~]# sed &＃39;/Never/ &＃61;&＃39;poetry1

1)Never give up,2

2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

!&＃xff1a;条件取反

[root&＃64;localhost ~]# sed &＃39;/Never/ !d&＃39;poetry #不删除被默认匹配的行1)Never give up,2)Never lose hope.

s///&＃xff1a;查找替换&＃xff0c;分割符可以自定义&＃xff0c;比如使用s&＃64;&＃64;&＃64;flag或者s###flag&＃xff0c;默认会替换被匹配的第一个位置&＃xff0c;但是可以添加替换标记&＃xff1a;

s///g&＃xff1a;全局替换

[root&＃64;localhost ~]# catpoetry1)Never give up,2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

[root&＃64;localhost~]# sed &＃39;s/\/your/g&＃39;poetry1)Never give up,2)Never lose hope.3)Always have faith,4)It allows your to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength your will gain

View Code

sed默认支持的基本的正则表达式&＃xff0c;使用-r, --regexp-extended选项可以支持扩展的正则表达式。

练习1&＃xff1a;删除/boot/grub2/grub.cfg文件中所有以空白字符开头的行的行首的所有空白字符

[root&＃64;localhost ~]# sed -r &＃39;s&＃64;^[[:space:]]&＃43;&＃64;&＃64;g&＃39; /boot/grub2/grub.cfg

View Code

练习2&＃xff1a;删除/etc/fstab文件中所有以#开头的行的行首的#号及#后面的所有空白字符

[root&＃64;localhost ~]# sed &＃39;s/^#[[:space:]]*//g&＃39; /etc/fstab

View Code

练习3&＃xff1a;输出一个目录给sed&＃xff0c;取出其目录&＃xff0c;类似于dirname

[root&＃64;localhost ~]# echo "/var/log/messages" | sed -r &＃39;s&＃64;[^/]&＃43;/?$&＃64;&＃64;&＃39;

/var/log/[root&＃64;localhost~]#

[root&＃64;localhost~]# echo "/var/log/messages/" | sed -r s&＃64;[^/]&＃43;/?$&＃64;&＃64;&＃39;

/var/log/

高级编辑命令

sed还有一些高级的命令&＃xff0c;会用到之前说到的保持空间。

举一些例子来看一下吧&＃xff01;

[root&＃64;localhost ~]# catpoetry1)Never give up,2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

可以自己先思考一下答案&＃xff0c;再点开&＃xff1a;

[root&＃64;localhost ~]# sed -n &＃39;n;p&＃39;poetry #只显示偶数行2)Never lose hope.4)It allows you to cope.6)As they always do.8)Your dreams will come true.10)You&＃39;ll live through your pain.

12)And strength you will gain

sed -n &＃39;n;p&＃39; poetry

[root&＃64;localhost ~]# sed &＃39;1!G;h;$!d&＃39;poetry #逆序显示12)And strength you will gain11)Know it will pass,10)You&＃39;ll live through your pain.

9)So put on a smile,8)Your dreams will come true.7)Just have patience,6)As they always do.5)Trying times will pass,4)It allows you to cope.3)Always have faith,2)Never lose hope.1)Never give up,

sed &＃39;1!G;h;$!d&＃39; poetry

[root&＃64;localhost ~]# sed &＃39;$!d&＃39; poetry #只保留最后一行&＃xff0c;类似tail -1

12)And strength you will gain

sed &＃39;$!d&＃39; poetry

[root&＃64;localhost ~]# sed &＃39;$!N;$!D&＃39;poetry #取出最后两行11)Know it will pass,12)And strength you will gain

sed &＃39;$!N;$!D&＃39; poetry

[root&＃64;localhost ~]# sed &＃39;G&＃39;poetry #在每一行的后面添加一个空白行1)Never give up,2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

sed &＃39;G&＃39; poetry

这些都是一些高级的用法&＃xff0c;在工作中用的可能比较少&＃xff0c;因为有的结果完全可以用其他简单的命令去实现。

循环和分支

sed最牛逼之处莫过于这个了&＃xff0c;sed提供了一个循环和分支工来控制程序的执行流程。

循环

sed循环的工作原理类似于现代编程语言中的goto语句。

定义sed的标签&＃xff1a;

:label

跳转到标签的位置&＃xff0c;使用b命令后面跟着标签名即可&＃xff0c;下面我们来看一个具体的实例&＃xff1a;

[root&＃64;localhost ~]# catteleplay

剧名&＃xff1a;白夜追凶

评分&＃xff1a;9.0剧名&＃xff1a;秘密深林

评分&＃xff1a;9.3剧名&＃xff1a;权利的游戏第七季

评分&＃xff1a;9.3剧名&＃xff1a;请回答1988

评分&＃xff1a;9.6[root&＃64;localhost~]# sed -n &＃39;h;n;H;x

s&＃64;\n&＃64;&＃xff0c;&＃64;/请回答/!b label

s&＃64;^&＃64;---&＃64;

:label

p&＃39;teleplay

剧名&＃xff1a;白夜追凶&＃xff0c;评分&＃xff1a;9.0剧名&＃xff1a;秘密深林&＃xff0c;评分&＃xff1a;9.3剧名&＃xff1a;权利的游戏第七季&＃xff0c;评分&＃xff1a;9.3

---剧名&＃xff1a;请回答1988&＃xff0c;评分&＃xff1a;9.6

分析&＃xff1a;

由于命令很长&＃xff0c;我们可以将命令分行来写&＃xff0c;当然也可以写在一行里面&＃xff1a;

1.h;n;H;x&＃xff1a;将第一行内容读取到模式空间&＃xff0c;执行h&＃xff0c;将模式空间的内容覆盖至保持空间&＃xff0c;执行n&＃xff0c;从文件中读取第二行覆盖至模式空间&＃xff0c;执行H&＃xff0c;将模式空间的内容追加至保持空间&＃xff0c;执行x&＃xff0c;将保持空间的内容和模式空间调换&＃xff1b;(这里得到的结果就是模式空间中存在两行)&＃xff1b;

2.s&＃64;\n&＃64;&＃xff0c;&＃64;&＃xff0c;将换行符替换为逗号&＃xff1b;这样原来的两行就变成了一行&＃xff1b;

3./请回答/!b label&＃xff0c;判断这一行中是否有“请回答”三个字符&＃xff0c;如果没有则直接跳到":label"&＃xff0c;然后执行打印"p"&＃xff0c;打印模式空间中的内容&＃xff0c;如果有则执行"s&＃64;^&＃64;---&＃64;"&＃xff0c;将在行首添加字符"---"。

这样一来&＃xff0c;只有"剧名&＃xff1a;请回答1988&＃xff0c;评分&＃xff1a;9.6"被匹配&＃xff0c;然后进行了行首的替换操作。

分支

可以使用t来创建分支。使用t命令跳转到指定的标签&＃xff0c;一样我们来看一个例子&＃xff1a;

[root&＃64;localhost ~]# sed -n &＃39;>h;n;H;x> s/\n/&＃xff0c;/

>:loop> /白夜追凶/s/^/-/

> /-----/!t loop> p&＃39;teleplay

-----剧名&＃xff1a;白夜追凶&＃xff0c;评分&＃xff1a;9.0剧名&＃xff1a;秘密深林&＃xff0c;评分&＃xff1a;9.3剧名&＃xff1a;权利的游戏第七季&＃xff0c;评分&＃xff1a;9.3剧名&＃xff1a;请回答1988&＃xff0c;评分&＃xff1a;9.6

分析&＃xff1a;

由于命令很长&＃xff0c;我们可以将命令分行来写&＃xff0c;当然也可以写在一行里面&＃xff1a;

1&＃xff1a;h;n;H;x&＃xff1a;将第一行内容读取到模式空间&＃xff0c;执行h&＃xff0c;将模式空间的内容覆盖至保持空间&＃xff0c;执行n&＃xff0c;从文件中读取第二行覆盖至模式空间&＃xff0c;执行H&＃xff0c;将模式空间的内容追加至保持空间&＃xff0c;执行x&＃xff0c;将保持空间的内容和模式空间调换&＃xff1b;(这里得到的结果就是模式空间中存在两行)&＃xff1b;

2&＃xff1a;s&＃64;\n&＃64;&＃xff0c;&＃64;&＃xff0c;将换行符替换为逗号&＃xff1b;这样原来的两行就变成了一行&＃xff1b;

3&＃xff1a;:loop&＃xff1a;定义了一个loop标签&＃xff1b;

4&＃xff1a;/白夜追凶/s/^/-/&＃xff1a;是否匹配模式&＃xff0c;如果匹配则在其行首添加一个"-"&＃xff1b;如果不匹配&＃xff0c;则直接打印&＃xff1b;

5&＃xff1a;/-----/!t loop&＃xff1a;是否存在5个"-"&＃xff0c;如果不存在&＃xff0c;则跳到标签loop处&＃xff0c;继续执行第4步添加"-"&＃xff0c;直到满足5个"-"&＃xff0c;则跳出循环打印。

最后&＃xff0c;我们之前的所有的操作&＃xff0c;都是没有修改文件的本身的&＃xff0c;可以使用 -i 选项来直接修改文件本身&＃xff0c;慎用&＃xff0c;建议在使用之前&＃xff0c;先备份一下文件&＃xff01;

[root&＃64;localhost ~]# sed -i &＃39;1d&＃39;poetry

[root&＃64;localhost~]#

[root&＃64;localhost~]# catpoetry2)Never lose hope.3)Always have faith,4)It allows you to cope.5)Trying times will pass,6)As they always do.7)Just have patience,8)Your dreams will come true.9)So put on a smile,10)You&＃39;ll live through your pain.

11)Know it will pass,12)And strength you will gain

总结&＃xff1a;sed的确是一个强大的文本处理工具&＃xff0c;功能非常丰富&＃xff0c;需要在今后的日常使用和工作中不断的熟悉和巩固。