17 个案例带你 5 分钟搞定 Linux 正则表达式

栏目: IT技术 · 发布时间: 2个月前

来源: mp.weixin.qq.com

内容简介:正则表达式是一种字符模式,用于在查找过程中匹配制定的字符。

本文转载自:http://mp.weixin.qq.com/s?__biz=MzA4Nzg5Nzc5OA==&mid=2651682876&idx=1&sn=a22e67c01df1e63b15f126a2bfef3ad4,本站转载出于传递更多信息之目的,版权归原作者或者来源机构所有。

17 个案例带你 5 分钟搞定  <a href='http://www.codercto.com/category/linux.html'>Linux</a>  正则表达式

17 个案例带你 5 分钟搞定 Linux 正则表达式

正则表达式是一种字符模式,用于在查找过程中匹配制定的字符。

元字符通常在Linux中分为两类:

  1. Shell元字符,由Linux Shell进行解析;

  2. 正则表达式元字符,由vi/grep/sed/awk等文本处理 工具 进行解析;

正则表达式一般以文本行进行处理,在进行下面实例之前,先为grep命令设置—color参数:

$ alias grep='grep --color=auto'

这样每次过滤出来的字符串都会带色彩了。

在开始之前还需要做一件事情,就是创建一个测试用的re-file文件,内容如下:

$ cat re-file
I had a lovely time on our little picnic.
Lovers were all around us. It is springtime. Oh
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
is forever. I live for you. It's hard to get back in the
groove.

正则表达式元字符

17 个案例带你 5 分钟搞定 Linux 正则表达式

  • 特殊的元字符

17 个案例带你 5 分钟搞定 Linux 正则表达式

  • 扩展的正则表达式

17 个案例带你 5 分钟搞定 Linux 正则表达式

实操

  • 匹配以love开头的所有行

$ grep '^love' re-file
love, how much I adore you. Do you know
  • 匹配love结尾的所有行

$ grep 'love$' re-file
clover. Did you see them?  I can only hope love.
  • 匹配以l开头,中间包含两个字符,结尾是e的所有行

$ grep 'l..e' re-file
I had a lovely time on our little picnic.
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
is forever. I live for you. It's hard to get back in the
  • 匹配0个或多个空行,后面是love的字符

$ grep ' *love' re-file
I had a lovely time on our little picnic.
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
  • 匹配love或Love

$ grep '[Ll]ove' re-file  # 对l不区分大小写
I had a lovely time on our little picnic.
Lovers were all around us. It is springtime. Oh
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
  • 匹配A-Z的字母,其次是ove

$ grep '[A-Z]ove' re-file
Lovers were all around us. It is springtime. Oh
  • 匹配不在A-Z范围内的任何字符行,所有的小写字符

$ grep '[^A-Z]' re-file
I had a lovely time on our little picnic.
Lovers were all around us. It is springtime. Oh
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
is forever. I live for you. It's hard to get back in the
groove.
  • 匹配love.

$ grep 'love\.' re-file
clover. Did you see them?  I can only hope love.
  • 匹配空格

$ grep '^$' re-file
  • 匹配任意字符

$ grep '.*' re-file
I had a lovely time on our little picnic.
Lovers were all around us. It is springtime. Oh
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
is forever. I live for you. It's hard to get back in the
groove.
  • 前面o字符重复2到4次

$ grep 'o\{2,4\}' re-file
groove.
  • 重复o字符至少2次

$ grep 'o\{2,\}' re-file
groove.
  • 重复0字符最多2次

$ grep 'o\{,2\}' re-file
I had a lovely time on our little picnic.
Lovers were all around us. It is springtime. Oh
love, how much I adore you. Do you know
the extent of my love? Oh, by the way, I think
I lost my gloves somewhere out in that field of
clover. Did you see them?  I can only hope love.
is forever. I live for you. It's hard to get back in the
groove.
  • 重复前一个字符一个或一个以

$ egrep "go+d" linux.txt
Linux is a good
god assdxw bcvnbvbjk
gooodfs awrerdxxhkl
good
  • 0个或者一个字符

ansheng@Ubuntu:/tmp$ egrep "go?d" linux.txt
god assdxw bcvnbvbjk
gdsystem awxxxx
  • 或,查找多个字符串

$ egrep "gd|good" linux.txt
Linux is a good
gdsystem awxxxx
good
  • 分组过滤匹配

$ egrep "g(la|oo)d" linux.txt
Linux is a good
glad
good

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17 个案例带你 5 分钟搞定 Linux 正则表达式

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