Conditionally source nix-profile if needed on non-nixos machines

installers/install-nix-packages-flake.sh

@@ -4,6 +4,15 @@
 
 set -ex
 
+if ! which nix &>/dev/null; then
+  if [ -r "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
+    . "$HOME/.nix-profile/etc/profile.d/nix.sh"
+  else
+    echo "Nix isn't available. Exiting now!"
+    exit 1
+  fi
+fi
+
 nix_packages=(
   # Personal tools
   "vimHugeX"