三剑客之grep

实例文件下载：

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

例题一：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.

例题二：反选

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

例题三：查找特定字符不论大小写

[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.

例题四：利用中括号[]来查找集合字符

1、查找test和taste这两个单词

[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：其实[]里面不论有几个字符，他都代表“一个”字符

例题五：查找不是以g开头的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：你发现18、19行还是有g开头，这是因为该行tool是被接受的

例题六：查找不是以字母开头的oo字符

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

总结：我们可以使用[a-z][A-Z][0-9]等方式来写，如果要求字符串是数字加字母，可以写成[a-zA-Z0-9]

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

例题七：查找以the开头

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

例题八：查找以小写字母开头

[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.

例题九：查找不是英文字母开头

[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:在中括号里面和外面含义是不同的，在括号里面标示反选，在括号外面表示行首

例题十：查找以.点结尾的

[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：因为小数点具有特殊含义，所以必须使用转义符（\）

例题十一：查找空白行

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

例题十二：任意一个字符.点与任意重复字符*

.代表一定有一个任意字符的意思

*代表重复前面字符0到无穷个

1、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.

2、查找两个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!

3、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!

4、查找g开头与g结尾的字符串，当中字符串可有可无

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.

5、查找任意数字的字符

[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.

例题十三：查找2-5个o的连续字符串

[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!

例题十四：查找g开头2-5个o的连续字符串，然后g结尾

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