Warning: command line geekiness ahead.
When writing shell scripts, I often send interactive output to the user via echo to give feedback or information. But if the shell script is called on a schedule via OS X's behind-the-scenes process launcher launchd, rather than from a Terminal session, chances are that I won't ever see that message.
Fortunately, it's relatively easy to figure out if a shell script has been called from launchd or not, simply by checking the $PPID variabl
