Debug Mac OSx

Starting up in single-user or verbose mode

1. Shut down your Mac if it is on.
2. Press the power button to start the computer.
3. Immediately press and hold the Command (Apple) key and one of the following:
- the "s" key for single-user mode. (Command-S)
- the "v" key for verbose mode. (Command-V)

Remounting read-write

mount -o update /