linux grep 文档搜索命令

grep 文本搜索工具
（global search regular expression(RE) and print out the line）

常用参数：

-w (word regexp)匹配整词
-x (line regexp)匹配整行
-i（ignore case） 不区分大小写
-E 使用正则表达式
-r 递归调用

-c (count)只输出匹配行数量
-n (line number) 显示匹配行及行号
-H 每一个匹配项显示文件名
-m[num] (max num) 最大匹配次数
-o (only match) 只输出匹配项
-l 只打印包含搜索项的文件名

-A[num] 打印匹配内容前num行
-B[num] 打印匹配内容后num行
-C[num] 打印匹配内容前后num行


测试文本内容，两个文件(a.txt,b.html)内容一致

I am sailing, I am sailing
home again 'cross the sea.
I am sailing stormy waters,
to be near you, to be free.
I am flying, I am flying
like a bird 'cross the sky.
I am flying
passing high clouds,
to be near you,
to be free.
Can you hear me,
can you hear me,
through the dark night far away?
I am dying,
forever crying, to be with you;
who can say?
Can you hear me,

#默认搜索
> grep "flying" a.txt
I am flying, I am flying
I am flying

#查看匹次数
> grep -c "am" a.txt
5

#打印匹配行号
> grep -n "am" a.txt
1:I am sailing, I am sailing
3:I am sailing stormy waters,
5:I am flying, I am flying
7:I am flying
14:I am dying,

#完全匹配单词，无输出
> grep -nw "sail" a.txt

#完全匹配单词
> grep -nw "sailing" a.txt
1:I am sailing, I am sailing
3:I am sailing stormy waters,

#匹配整行
> grep -nx "sailing" a.txt
> grep -nx "I am flying" a.txt
7:I am flying

#-i不区分大小写
> grep -n "AM" a.txt
> grep -ni "AM" a.txt
1:I am sailing, I am sailing
3:I am sailing stormy waters,
5:I am flying, I am flying
7:I am flying
14:I am dying,

#显示匹配文件名
> grep -H "am" a.txt
a.txt:I am sailing, I am sailing
a.txt:I am sailing stormy waters,
a.txt:I am flying, I am flying
a.txt:I am flying
a.txt:I am dying
#最大匹配2次结束
> grep -H -m2 "am" a.txt
a.txt:I am sailing, I am sailing
a.txt:I am sailing stormy waters,

#使用正则
> grep -E "fly+" a.txt
I am flying, I am flying
I am flying

#-o只显示匹配内容
> grep -E  "fly\S+" -o a.txt
flying,
flying
flying

#显示匹配内容前后行控制
> grep -n "high" a.txt
8:passing high clouds,
#显示匹配内容的前三行
> grep -n -A3 "high" a.txt
8:passing high clouds,
9-to be near you,
10-to be free.
11-Can you hear me,
#显示匹配内容的后三行
> grep -n -B3 "high" a.txt
5-I am flying, I am flying
6-like a bird 'cross the sky.
7-I am flying
8:passing high clouds,
#显示匹配内容的前后三行
> grep -n -C3 "high" a.txt
5-I am flying, I am flying
6-like a bird 'cross the sky.
7-I am flying
8:passing high clouds,
9-to be near you,
10-to be free.
11-Can you hear me,

#-r递归查询  
> grep -H "high" -r . --include *.txt
./a.txt:passing high clouds,

#查询多个匹配项
> grep -e "high" -e "near" a.txt
to be near you, to be free.
passing high clouds,
to be near you,

#显示匹配文件名
> grep -l "high" *
a.txt
b.html