Terminal commands for disk repair

Sure it can! Reboot into recovery and use Disk Utility there. Or use an external bootable drive of the same OS version to do it. Terminal won’t work if the drive is the booting drive.

The best way to think this is your shoes heel comes off and you walk into the shoe cobbler to get your shoe fixed can he fix it with you wearing the shoe? Nope, you need to take it off so he can work on it!

Same deal here you can’t be using the disk as your boot drive as the files are then open and can’t be fixed. Recovery is using the Internet and RAM not the drive its self. Or, using an external drive which is how I do it as its faster!