Linux View Log Common commands

1. View Log common commands tail:-n is the display line number, equivalent to the NL command; examples are as follows: tail-100f Test.log Real-time monitoring of 100 rows of logs

Tail-n test.log query log at the end of the last 10 lines;

Tail-n +10 test.log Query all logs after 10 lines;

Head

Contrary to tail, tail is the number of rows of logs after the look, examples are as follows:

Head-n test.log Query log file in the first 10 rows of logs;

Head-n -10 test.log query log file except for all other logs in the last 10 lines;

Cat

TAC is in reverse view, is the cat word anti-write;

cat-n test.log |grep "Debug" Query keyword log

2. Application Scenario One: View by line number---filter out logs near keywords

1) cat-n test.log |grep "Debug" to get the line number of the critical log

2) cat-n test.log |tail-n +92|head-n 20 Select the middle row where the keyword is located. Then look at the first 10 lines of this keyword and the next 10 lines of logs:

Tail-n +92 indicates a log after querying 92 rows

Head-n 20 indicates that the first 20 records are checked in the previous query results.

3. Scenario two: Querying logs by date

Sed-n '/2014-12-17 16:17:20/,/2014-12-17 16:17:36/p ' Test.log

Special Note: The above two dates must be printed in the log log, otherwise invalid;

First grep ' 2014-12-17 16:17:20 ' test.log to determine if there is a point in the log

4. Application Scenario Three: The log content is very much, printing on the screen is not easy to view

(1) using the more and less commands,

such as: Cat-n test.log |grep "Debug" |more so that the page printing, by clicking the Space bar to page

(2) Save it to a file using >xxx.txt, then you can pull down this file to analyze

such as: Cat-n test.log |grep "Debug" >debug.txt

Linux View Log Common commands