Fetch nix location from nix-script

scripts/Common/OS/setup.fish

@@ -3,6 +3,7 @@ function runSetup
     set -l dir (status dirname)
     source "$dir/../../lib/settings.fish"
     source "$dir/../../lib/hooks.fish"
+    source "$dir/../../lib/nix.fish"
 
     if [ -z "$CONFIG_NAME" ]
         selectProfile config
@@ -51,9 +52,8 @@ function runSetup
     and echo "Preparing nix..."
 
     and begin
-        set -l channelDir /nix/var/nix/profiles/per-user/root/channels/nixpkgs
-        mkdir -p (dirname "$mountDir/$channelDir")
-        cp -r "$channelDir" "$mountDir/$channelDir"
+        mkdir -p (dirname "$mountDir/$nixPkgsDir")
+        cp -r "$nixPkgsDir" "$mountDir/$nixPkgsDir"
     end
 
     and echo "Installing dependencies..."