Use grep to query logs

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linux system by printing the matched grep vertical lines

 

If you just want a few lines above and below the matching pattern, grep can be achieved.

 

$ Grep -5 'parttern' inputfile // print five lines before and after matching lines

 

Front $ grep -C 5 'parttern' inputfile // print matching rows 5 rows

 

After row 5 $ grep -A 5 'parttern' inputfile // print matching lines

 

$ grep -B 5 'parttern' inputfile // print the first 5 rows of matching lines

to view the mysql slow log ip address is 192.168.0.10 SQL statements sent from the back three rows

1. tail -50 /usr/local/mysql/data/sql-slow.log |grep -3 '192.168.0.10'  

Match one field php error log

　　2，tail -100 /data/logs/php/php_error_5.3.log  | grep  "Memcache::get()";

View a file line 5 and a line 10

 sed -n '5,10p' filename so you can view only the fifth line of the file to the line 10.