grep 精确匹配

使用grep实现精确过滤的五种方法

（1）当被过滤的内容占据一行时

[[email protected] scripts]# cat oldboy.log        

200

0200

2000

[[email protected] scripts]# grep "\b200\b" oldboy.log  

200 #<==正则按单词匹配

[[email protected] scripts]# grep -w "200" oldboy.log                  

200 #<==按单词匹配

[[email protected] scripts]# grep -x "200" oldboy.log                  

200 #<==按整行匹配

[[email protected] scripts]# grep "^200$" oldboy.log  

200 #<==正则开头结尾匹配，相当于整行匹配

[[email protected] scripts]# grep -E "\<200\>" oldboy.log  

200 #<==扩展正则

（2）当被过滤的内容占据一行的一部分

[[email protected] scripts]# cat oldboy.log  

200 oldboy

0200 oldgirl

2000 littleboy

[[email protected] scripts]# grep "\b200\b" oldboy.log

200 oldboy

[[email protected] scripts]# grep -w "200" oldboy.log

200 oldboy

[[email protected] scripts]# grep -x "200" oldboy.log

#<==按整行匹配，所以没结果

[[email protected] scripts]# grep -x "200 oldboy" oldboy.log

200 oldboy

[[email protected] scripts]# grep "^200$" oldboy.log

#<==按整行匹配，所以没结果

[[email protected] scripts]# grep "^200 oldboy$" oldboy.log

200 oldboy

[[email protected] scripts]# grep -E "\<200\>" oldboy.log  

200 oldboy