“Single User” is a boot mode, you actually tells the unix shell that the OS should load only prompt (no GUI), and the local console login is the only login available (can’t be logged on from the network). Now the question is why we need to boot in Single User mode and the answer is, sometimes the system requires an administrative actions by the administrator, such as disk checkup, partition altering, drivers uninstalling, backups, etc.at this delicate tasks you don’t want other users to touch/create/remove/use files, hardware, CPU, and use resources. this is why you enter into single user mode.
What can you do in “Single User” Mode?
since single user mode is for administrator and no GUI is available then every task you can do from terminal (command line) as root user you can do here, which is practically everything (on the current system) it wasn’t meant to be used for regular work such as surfing the web (there is no network) or reading files etc. you can use all the unix commands available for OS X and all the command line utilities and applications available on that machine.
How to enter Single User Mode :
- Restart your Mac or Hackintosh.
- Continuously press F8 until you see the Darwin boot prompt
- Type “-s” without the quotation marks and press enter.
- You will soon reach a command prompt
- Note the lines written to the console about fsck and mount
- Type : /sbin/fsck -fy
- Type : /sbin/mount – uw / this will mount your file system
- thats it now you are in “Single User Mode”
In single-user mode, not all functions of Mac OS X are available. To use the Mac OS X interface or other high-level aspects of Mac OS X, you need to start up in the standard mode.To switch back to the Mac OS X interface, type reboot and press the Return key. The computer restarts and you see the login dialog or the Mac desktop, depending on your login preferences.