MacOS X: single user mode

Single-user mode may be used for troubleshooting, include reseting forgoten root password.

Shut down your Mac in case that it running. Press the power button to start computer, immediately press and hold the Command (Apple) key and the "s" key for starting MacOS X in single-user mode.

You have successfully entered single-user or verbose mode when you see white text appear on the screen.

If you want to reset your root password tape the "/sbin/mount -wu /" for mount file system in read-write mode, then "passwd root" for change root password (even in you don't known password)

To exit single-user mode type "reboot" then press Return.

Single-User Mode in HP-UX

Single-user mode is very useful for maintenance (e.g. in case if you forgot root password).

To boot HP-UX in single-user mode at HP 9000 Systems (PA-RISC) you need to stop boot process by pressing any key during booting: