No – this has nothing to do with nappy changing! I’ve spent the past two weeks as part of the support team for a customer’s WebSphere Application Server environment. Although I know all the theory (I’m an IBM Certified System Administrator for Versions 5.0, 6.0 and 6.1) it’s not very often I spend long enough at any one customer to get my hands dirty. My Korn shell scripting, Jython and vi skills certainly improved rapidly during the time I was there!
One moderately interesting job I had to do related to the processing of heap dumps. These were being directed to a separate file system using the file option on the JVM arguments. However, when that file system filled up dumps would then default back to /tmp and when this gets full, bad things start to happen. Consequently, the plan was to write a script to clear out old dumps to make space. The cunning part was to use the tool option to execute the script just before a new heap dump is created. The exact syntax used was as follows:
-Xdump:tool:events=user+abort,range=1..0,
exec=/some/path/cleanup.sh,priority=999
Thanks to Andy Simms and Pete Daly for the research behind this one.