三劍客之grep

實例文件下載：

wget http://linux.vbird.org/linux_basic/0330regularex/regular_express.txt

例題一：查找特定字符

[root@mail_bk tmp]# grep -n 'the' regular_express.txt
8:I can't finish the test.
12:the symbol '*' is represented as start.
15:You are the best is mean you are the no. 1.
16:The world <Happy> is the same with "glad".
18:google is the best tools for search keyword.

例題二：反選

[root@mail_bk tmp]# grep -nv 'the' regular_express.txt

例題三：查找特定字符不論大小寫

[root@mail_bk tmp]# grep -ni 'the' regular_express.txt
8:I can't finish the test.
9:Oh! The soup taste good.
12:the symbol '*' is represented as start.
14:The gd software is a library for drafting programs.
15:You are the best is mean you are the no. 1.
16:The world <Happy> is the same with "glad".
18:google is the best tools for search keyword.

例題四：利用中括號[]來查找集合字符

一、查找test和taste這兩個單詞

[root@mail_bk tmp]# grep -n 't[a-z]st' regular_express.txt
8:I can't finish the test.
9:Oh! The soup taste good.

或者

[root@mail_bk tmp]# grep -n 't[ae]st' regular_express.txt
8:I can't finish the test.
9:Oh! The soup taste good.

注：其實[]裏面不論有幾個字符，他都表明「一個」字符

例題五：查找不是以g開頭的oo字符

[root@mail_bk tmp]# grep -n '[^g]oo' regular_express.txt
2:apple is my favorite food.
3:Football game is not use feet only.
18:google is the best tools for search keyword.
19:goooooogle yes!

注：你發現1八、19行仍是有g開頭，這是由於該行tool是被接受的

例題六：查找不是以字母開頭的oo字符

[root@mail_bk tmp]# grep -n '[^a-z]oo' regular_express.txt
3:Football game is not use feet only.

總結：咱們可使用[a-z][A-Z][0-9]等方式來寫，若是要求字符串是數字加字母，能夠寫成[a-zA-Z0-9]

[root@mail_bk tmp]# grep -n '[a-zA-Z0-9]' regular_express.txt

例題七：查找以the開頭

[root@mail_bk tmp]# grep -n '^the' regular_express.txt
12:the symbol '*' is represented as start.

例題八：查找以小寫字母開頭

[root@mail_bk tmp]# grep -n '^[a-z]' regular_express.txt   
2:apple is my favorite food.
4:this dress doesn't fit me.
10:motorcycle is cheap than car.
12:the symbol '*' is represented as start.
18:google is the best tools for search keyword.
19:goooooogle yes!
20:go! go! Let's go.

例題九：查找不是英文字母開頭

[root@mail_bk tmp]# grep -nv '^[a-zA-Z]' regular_express.txt
1:"Open Source" is a good mechanism to develop programs.
21:# I am VBird
22:

或者：

[root@mail_bk tmp]# grep -n '^[^a-zA-Z]' regular_express.txt
1:"Open Source" is a good mechanism to develop programs.
21:# I am VBird

注意:在中括號裏面和外面含義是不一樣的，在括號裏面標示反選，在括號外面表示行首

例題十：查找以.點結尾的

[root@mail_bk tmp]# grep -n '\.$' regular_express.txt 
1:"Open Source" is a good mechanism to develop programs.
2:apple is my favorite food.
3:Football game is not use feet only.
4:this dress doesn't fit me.
10:motorcycle is cheap than car.
11:This window is clear.
12:the symbol '*' is represented as start.
15:You are the best is mean you are the no. 1.
16:The world <Happy> is the same with "glad".
17:I like dog.
18:google is the best tools for search keyword.
20:go! go! Let's go.

注意：由於小數點具備特殊含義，因此必須使用轉義符（\）

例題十一：查找空白行

[root@mail_bk tmp]# grep -n '^$' regular_express.txt
22:

例題十二：任意一個字符.點與任意重複字符*

.表明必定有一個任意字符的意思

*表明重複前面字符0到無窮個

一、查找g？？d的字符

[root@mail_bk tmp]# grep -n 'g..g' regular_express.txt  
18:google is the best tools for search keyword.

二、查找兩個o以上的字符串

[root@mail_bk tmp]# grep -n 'ooo*' regular_express.txt
1:"Open Source" is a good mechanism to develop programs.
2:apple is my favorite food.
3:Football game is not use feet only.
9:Oh! The soup taste good.
18:google is the best tools for search keyword.
19:goooooogle yes!

三、查找gog，goog，gooog字符

[root@mail_bk tmp]# grep -n 'go*g' regular_express.txt    
18:google is the best tools for search keyword.
19:goooooogle yes!

四、查找g開頭與g結尾的字符串，當中字符串無關緊要

1:"Open Source" is a good mechanism to develop programs.
14:The gd software is a library for drafting programs.
18:google is the best tools for search keyword.
19:goooooogle yes!
20:go! go! Let's go.

五、查找任意數字的字符

[root@mail_bk tmp]# grep -n '[0-9][0-9]*' regular_express.txt       
5:However, this dress is about $ 3183 dollars.
15:You are the best is mean you are the no. 1.

例題十三：查找2-5個o的連續字符串

[root@mail_bk tmp]# grep -n 'o\{2,5\}' regular_express.txt  
1:"Open Source" is a good mechanism to develop programs.
2:apple is my favorite food.
3:Football game is not use feet only.
9:Oh! The soup taste good.
18:google is the best tools for search keyword.
19:goooooogle yes!

例題十四：查找g開頭2-5個o的連續字符串，而後g結尾

[root@mail_bk tmp]# grep -n 'go\{2,5\}g' regular_express.txt
18:google is the best tools for search keyword.