Nix : Add update funs.

.config/bash/module/Nix.sh

@@ -17,3 +17,18 @@ function nix_find() {
 		false
 	fi
 }
+
+# Switch to Unstable branch.
+function nix_unstable() {
+	nix-channel --add https://nixos.org/channels/nixos-unstable nixos
+}
+
+# Switch to Small Unstable branch (for server).
+function nix_unstable_small() {
+	nix-channel --add https://nixos.org/channels/nixos-unstable-small nixos
+}
+
+# Update system.
+function nix_update() {
+	nixos-rebuild switch --upgrade
+}