Scala REPL: There were deprecation warnings, re-run with -deprecation

Whenever I used to get the Scala REPL warning message, "There were deprecation warnings, re-run with -deprecation", I used to have to restart the REPL with the -deprecation flag to see the warning message, like this:

$ scala -deprecation

That works, but sadly, you had to lose your entire REPL session to run it.

Use :warnings

Thanks to the Scala gods, this is no longer necessary in Scala 2.10 (and newer). Now, when you get the REPL deprecation warning message, like this:

How to put SBT into offline mode with a command line setting

Scala SBT FAQ: How do I put SBT into offline mode so I can use it while working on an airplane, or any other location where I don't have a WiFi connection?

Use an SBT command like this to compile and run a project from your operating system command line:

$ sbt "set offline := true" run

I used this command a lot recently when I didn't have internet access, and I had to keep SBT from trying to reach out to the internet all the time.

How to start a Mac in safe mode

Mac question: Something just went wrong, and I need to start my Mac (or iMac) in safe mode, or something like safe mode? Can this be done on a Mac?

Answer: Yes, Mac computers support a "safe mode" boot process. Here are the steps needed to start your Mac/iMac in safe mode:

Error message: mv cannot unlink remove file, operation not permitted

I got this Unix/Linux error message today "mv: cannot unlink '/tmp/forms-1.2.1.jar': Operation not permitted" when trying to move (mv) the file forms-1.2.1.jar from the /tmp directory to another directory. The full error output looked like this: