To copy your files from Disk Utility to an external drive in macOS Recovery Mode, you need to use Terminal. Follow the steps below:
- Ensure the external hard drive is connected to your Mac.
- In Disk Utility, check the internal volumes and make sure they are all mounted. (If FileVault is enabled, the data volume will be grayed out and you need to unlock it by selecting it and entering the login password.)
- Close Disk Utility and choose Utilities > Terminal from the menu bar.
- To copy your user folder to the external drive, run:cp -R /Volumes/Macintosh\ HD/Users/user_name/ /Volumes/volume_name
Replace user_name with your user folder's name and volume_name with the external drive or partition's name.
For example, to move from a user folder called My Drive to an external drive named Data, the command should be: cp -R /Volumes/Macintosh\ HD/Users/My\ Drive/ /Volumes/Data
Note: If Terminal doesn't work, you can run data recovery software in macOS Recovery Mode to get all files out of the unbootable Mac.
If you want to learn more details about copying files in Terminal, take a look at: How to Copy a File/Directory in macOS Terminal with the cp command?