Here's a bit of strangeness I encountered.
I ran the command to zip up my home directory, and it seemed to be going OK. I checked every once in a while, and the backup.tgz file was larger each time, the last time I had checked, it was 3.3GB and still going strong.
When the command finished and I was returned to the prompt, the backup.tgz file was only 998MB in size. This is plainly impossable, as I have at least three ISO images in there, a full copy of my windows drive, and all the garbage I've collected since 1995.
Why does it seem that my backup.tgz file shrunk amazingly *after* the tar command finished?