Log message style guide

Question

I'm looking for a style guide to log messages:

For example:

• What & when
• Conventions
• Style & Formatting
• Readability

i.e. what makes a good / bad log message string

I'm particularly interested in what make a good log string - beyond including the TIME, SEVERITY and COMPONENT, as I tend to use log4j which gives me this information for free.

Answer 1

Whatever you decide, if it's a text log, start each line with a good timestamp in, preferably, ISO format:

YYYY-MM-DDTHH:MM:SS.mmm

In all likelihood, you will want to follow the timestamp with a severity code.

Some good logging guidelines can be found here:

http://watchitlater.com/blog/2009/12/logging-guidelines/

and here

http://download.oracle.com/docs/cd/B32110_01/web.1013/b28952/logging.htm

Answer 2

That really depends on your application. I may draw inspiration from anything at /var/log/*