I recently communicated with a Mac admin who was concerned about using FileVault 2 in his environment because he didn’t want to lose access to tools like single-user mode. Like a number of Mac admins, he’d found single-user mode valuable in helping to diagnose and fix issues on troublesome Macs.
Fortunately, Apple makes it reasonably easy to boot into single-user mode on a FileVault 2-encrypted system. Here’s how to boot into single-user on a FileVault 2-encrypted system:
1. Hold down Command-S after powering the system.
2. The Mac will be begin booting into single user, then the FileVault 2 pre-boot login screen will appear.
3. Authenticate at the FileVault 2 pre-boot login screen by selecting an account and providing the account’s password.
4. The Mac will then unlock and continue booting into single-user mode.
To show what this looks like, I’ve made a short video showing the process. In this instance, I booted into single-user mode and performed a disk check using fsck, then continued with the rest of the boot process.
