Nix on macOS Catalina

I'm writing this gist for my own records but it might help someone else too.

Installing Nix

Support for Catalina has improved a lot since the update was first rolled out.

Note: See the NixOS manual for discussion of the --darwin-use-unencrypted-nix-store-volume option.

Single-users

1. Run

   sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume --no-daemon

Multi-user

1. Run

   sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume --daemon

Uninstalling Nix

Single-user

1. Remove the mount from /etc/fstab by running

   sudo vifs

   and deleting the line LABEL=Nix\040Store /nix apfs rw,nobrowse.

2. Delete the APFS volume using diskutil

   diskutil apfs deleteVolume <volumeDevice>

Note: volumeDevice can be found by running

diskutil apfs list

3. Remove the synthetic empty directory for mounting at /nix by running

   sudo vim /etc/synthetic.conf

   and deleting the line nix.

4. Reboot the system for changes to take effect.

5. Run

   echo "removing nix files"
   sudo rm -rf /nix
   rm -rf ~/.nix-profile
   rm -rf ~/.nix-defexpr
   rm -rf ~/.nix-channels
   rm -rf ~/.nixpkgs
   rm -rf ~/.config/nixpkgs
   rm -rf ~/.cache/nix

   to remove all remaining Nix artifacts from the system.

Note: There may also be references to Nix in the shell configurations files under your home directory (e.g. ~/.profile, ~/.bash_profile, ~/.zshenv, etc.) which you may remove.

Multi-user

1. Kill the daemon process by running

   sudo launchctl unload /Library/LaunchDaemons/org.nixos.nix-daemon.plist

2. Remove the mount from /etc/fstab by running

   sudo vifs

   and deleting the line LABEL=Nix\040Store /nix apfs rw,nobrowse.

3. Delete the APFS volume using diskutil

   diskutil apfs deleteVolume <volumeDevice>

Note: volumeDevice can be found by running

diskutil apfs list

4. Remove the synthetic empty directory for mounting at /nix by running

   sudo vim /etc/synthetic.conf

   and deleting the line nix.

5. Reboot the system for changes to take effect.

6. Run

   echo "removing daemon"
   sudo rm /Library/LaunchDaemons/org.nixos.nix-daemon.plist
   
   echo "removing daemon created users and groups"
   USERS=$(sudo dscl . list /Users | grep nixbld)
   
   for USER in $USERS; do
       sudo /usr/bin/dscl . -delete "/Users/$USER"
       sudo /usr/bin/dscl . -delete /Groups/staff GroupMembership $USER;
   done
   
   sudo /usr/bin/dscl . -delete "/Groups/nixbld"
   
   echo "reverting system shell configurations"
   sudo mv /etc/profile.backup-before-nix /etc/profile
   sudo mv /etc/bashrc.backup-before-nix /etc/bashrc
   sudo mv /etc/zshrc.backup-before-nix /etc/zshrc
   
   echo "removing nix files"
   sudo rm -rf /nix
   sudo rm -rf /etc/nix
   sudo rm -rf /etc/profile/nix.sh
   sudo rm -rf /var/root/.nix-profile
   sudo rm -rf /var/root/.nix-defexpr
   sudo rm -rf /var/root/.nix-channels
   sudo rm -rf /var/root/.cache/nix
   rm -rf ~/.nix-profile
   rm -rf ~/.nix-defexpr
   rm -rf ~/.nix-channels
   rm -rf ~/.nixpkgs
   rm -rf ~/.config/nixpkgs
   rm -rf ~/.cache/nix

   to remove all remaining Nix artifacts from the system.