Fixed an Interesting Bug in Shell Script
This morning I noticed that the crontab job I had to cleaning up the stale, unused jars that happen when you have a project in jruby or clojrue where everything is in a single jar, and they are all tagged with the GitHub SHA to tell them apart. Actually, it's about the nicest thing about jruby and clojure because it means that you don't have to hassle with directories of files, and it's super easy to have a symlink to the current version and then de-reference it in the script with a little:
jar="$HOME/dark-magic-current.jar" actual_jar=`readlink $jar`
and then in the rest of the code for running the app, use $actual_jar and you can deploy on top of a running system without disturbing it. Restart, the script will pick up the new symlink, and you're in business. Pretty nice, actually.
Anyway, the bug was in the vacuum script:
line 26 used to read:
for i in "${oldJars}"; do
and I learned that because oldJars was a variable, what I was doing by quoting it was to make that one value for the loop - and not a series like I had hoped. Simply removing the quotes took care of the problem as bash is smart enough not to have thought the space-delimited names in the variable were actually separate commands.
Bash is smarter than I thought. Nice.
Simple fix, and now we are checking all the jars for expiration.