Saturday, July 2, 2016

How to find more needles

If you're someone like me who needs to find needles in log haystacks then bash and grep are surely your friends. Here are two tricks I've come to use to make my work easier.

Making errors scream!

Okay so you have four or five terminal tabs going tailing different but related logs and the logs keep on pilling up. A script like the one I got below should be useful (given that you have headphone on, unless you getting weird looks from people around you). 

The script tails a log periodically and checks for the existence of a word(or phrase). If a match is made it plays an audio file(wave) to get your attention.



Usage,

sh logchecker.sh <NO_OF_LINE_TO_TAIL> <LOG_FILE> <WORD_TO_LOOK_FOR> <WAV_FILE> 

Redirect errors to a file

You have a server with debug log level enable at the root. The logs are putting on MBs instead of KBs. Grep out what you need to a separate file to make analysis more manageable.



Usage,

sh grepout.sh <LOG_FILE> <NUM_LINES_BEFORE_MATCH> <NUM_LINE_AFTER_MATCH> <WORD_TO_MATCH> 

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