[toc]
定义
简单的来说就是用在字符串的处理上面的一项表达式。
基础表达式
<font color=red>注意：</font>不同的环境语系会导致不同选取结果，这里以LANG=C为例子。
常用特殊符号：| 特殊符号 | 代表意义 |
|---|---|
| [:alnum:] | 代表英文大小写字符以及数字 |
| [:digit:] | 代表数字 |
| [:alpha:] | 代表英文大小写 |
| [:blank:] | 代表空格键和tab键 |
| [:lower:] | 代表小写字符 |
| [:upper:] | 代表大写字符 |
| [:xdigit:] | 代表十六进制的数字类型 |
| 这里的可以用[a-z],[0-9]替代 |
基础命令
grep - [acinv]i:不区分大小写n:列出行号v:取反操作c:计算找到字符串的次数a:将binary文件以text文件的方式查找数据为方便下面的操作，我们需将系统环境设置为LANG=C，以及在～/.bashrc内加入alias grep='grep -color=auto'，最后source ~/.bashrc即可。Of course you can use command to get this file.wget http://linux.vbird.org/linux_basic/0330regularex/regular_express.tx
And you can see what's inside by using cat command
➜ Desktop cat regular_express.txt "Open Source" is a good mechanism to develop programs.apple is my favorite food.Football game is not use feet only.this dress doesn't fit me.However, this dress is about $ 3183 dollars.GNU is free air not free beer.Her hair is very beauty.I can't finish the test.Oh! The soup taste good.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.You are the best is mean you are the no. 1.The worldis 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