17個案例帶你3分鐘搞定Linux正則表達式

正則表達式是一種字符模式，用於在查找過程當中匹配製定的字符。

元字符一般在Linux中分爲兩類：

Shell元字符，由Linux Shell進行解析；

正則表達式元字符，由vi/grep/sed/awk等文本處理工具進行解析；

正則表達式通常以文本行進行處理，在進行下面實例以前，先爲grep命令設置--color參數：

 

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

這樣每次過濾出來的字符串都會帶色彩了。

在開始以前還須要作一件事情，就是建立一個測試用的re-file文件，內容以下：

 

$ 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.

文件內容摘錄自<<UNIX/SHELL範例精解第四版>>

 

$ cat linux.txt
Linux is a good 
god assdxw bcvnbvbjk
greatttttt  wexcvxc
operaaaating  dhfghfvx
gooodfs awrerdxxhkl
gdsystem awxxxx
glad
good

正則表達式元字符

特殊的元字符