Grep exact match

Use grep Five ways to achieve accurate filtering

（1） When the filtered content occupies a line

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

200

0200

2000

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

200 #<== Regular match by word

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

200 #<== Match by word

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

200 #<== Match by entire row

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

200 #<== Regular beginning and end match , It is equivalent to the whole line matching

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

200 #<== Extended regularization

（2） When the filtered content occupies part of a line

[[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

#<== Match by entire row , So there was no result

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

200 oldboy

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

#<== Match by entire row , So there was no result

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

200 oldboy

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

200 oldboy