共计 1114 个字符，预计需要花费 3 分钟才能阅读完成。
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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。练习文件摸我 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 world <Happy> is 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
