log4bash is a Log4J style logging utility for bash scripts.
Facilitates creating easy to read,and easy to parse, log files from your bash scripts.
Developers have the ability to override pretty much all of the default behavior.
If the developer chooses to let a user do so, they can pass flags to a script at run time to control some aspects of the logging output.
This includes displaying the logging output to the screen in addition to the log file, and altering the logging level.
There is a script included (test.log4bash.sh) that provides working code on how to use all of log4bash's features.
IF you are looking for a similar utility for shells other than bash, check out log4sh at http://freshmeat.net/projects/log4sh.
log4bash is licensed under the GNU LGPL v2.1 (Lesser GPL), so that it won't interfere with your script's copyright / IP.
The test script is licensed under the MIT license, so that you can pretty much do as you please with it
Download my log4bash here