Nicely written tutorial. The only thing I would suggest is always prefering [[ to [ because it makes dealing with parameter expansions much more easier. Also [[ is most likely as shell builtin, in contrast to [, which is most likely an external program.
> The only thing I would suggest is always prefering [[ to [ because it makes dealing with parameter expansions much more easier.
I wrote the article before Bash 3 was released, and the article remains appropriate for platforms that don't have Bash 3 abilities. If you read down in the article, you will see where I address this issue:
