diff --git a/README.md b/README.md
index 47f4a3c..b95c234 100644
--- a/README.md
+++ b/README.md
@@ -9,20 +9,24 @@ Run `ctl.sh` to see the list of commands to manage the system.
 ```bash
 ./ctl.sh
 
- ~> OS
+Usage: ctl.sh <command> <subcommand>
 
-    os-test           Rebuild and test OS without creating a new generation
-    os-rebuild        Rebuild OS and create new generation
-    os-upgrade        Upgrade channels and rebuild OS
+ ~> os
+
+    test              Rebuild and test OS without new generation
+    rebuild           Rebuild OS and create new generation
+    upgrade           Upgrade channels and rebuild OS
+    changes           Show changes between generations
+    gc                Garbage collect old generations
     vm                Build and run as VM
 
- ~> Store
+ ~> store
 
-    store-gc          Collecting garbage in nix-store
-    store-optimise    Optimise nix-store
+    gc                Collecting garbage in nix-store
+    optimise          Optimise nix-store
     search PACKAGE    Search for package
 
- ~> Shell
+ ~> shell
 
-    shell NAME        Run a nix-shell from ./shell/
+    run NAME          Run a nix-shell from ./shell/
 ```
diff --git a/ctl.sh b/ctl.sh
index af060a2..59b52fe 100755
--- a/ctl.sh
+++ b/ctl.sh
@@ -1,8 +1,26 @@
 #!/usr/bin/env bash
 
 ##
-## ~> OS
+##Usage: ctl.sh <command> <subcommand>
 ##
+## ~> os
+##
+##    test              Rebuild and test OS without new generation
+##    rebuild           Rebuild OS and create new generation
+##    upgrade           Upgrade channels and rebuild OS
+##    changes           Show changes between generations
+##    gc                Garbage collect old generations
+##    vm                Build and run as VM
+##
+## ~> store
+##
+##    gc                Collecting garbage in nix-store
+##    optimise          Optimise nix-store
+##    search PACKAGE    Search for package
+##
+## ~> shell
+##
+##    run NAME          Run a nix-shell from ./shell/
 
 function info {
 	clear
@@ -11,58 +29,53 @@ function info {
 	sed -n 's/^##//p' ctl.sh
 }
 
-##    os-test           Rebuild and test OS without creating a new generation
-function os-test {
-	sudo nixos-rebuild --flake ./os#nixos test
+function os {
+	function test {
+		sudo nixos-rebuild --flake ./os#nixos test
+	}
+	function rebuild {
+		echo "Rebuild OS"
+		sudo nixos-rebuild --flake ./os#nixos switch
+	}
+	function upgrade {
+		echo "Upgrade channels and rebuild OS"
+		sudo nixos-rebuild --upgrade --flake ./os#nixos switch
+	}
+	function changes {
+		nix profile diff-closures --profile /nix/var/nix/profiles/system
+	}
+	function gc {
+		sudo nix-collect-garbage -d
+		sudo nixos-rebuild switch
+	}
+	function vm {
+		echo "Build and run configuration as VM"
+		rm *.qcow2
+		nixos-rebuild build-vm --flake ./os#nixos && result/bin/run-*-vm
+	}
+	${@}
 }
 
-##    os-rebuild        Rebuild OS and create new generation
-function os-rebuild {
-	echo "Rebuild OS"
-	sudo nixos-rebuild --flake ./os#nixos switch
+function store {
+	function gc {
+		echo "Collecting garbage"
+		nix-store --gc --print-roots | egrep -v "^(/nix/var|/run/\w+-system|\{memory|/proc)"
+	}
+	function optimise {
+		echo "Optimizing nix-store. This may take a moment..."
+		nix-store --optimise
+	}
+	function search {
+		nix search nixpkgs $1
+	}
+	${@}
 }
 
-##    os-upgrade        Upgrade channels and rebuild OS
-function os-upgrade {
-	echo "Upgrade channels and rebuild OS"
-	sudo nixos-rebuild --upgrade --flake ./os#nixos switch
-}
-
-##    vm                Build and run as VM
-function vm {
-	echo "Build and run configuration as VM"
-	rm *.qcow2
-	nixos-rebuild build-vm --flake ./os#nixos && result/bin/run-*-vm
-}
-
-##
-## ~> Store
-##
-
-##    store-gc          Collecting garbage in nix-store
-function store-gc {
-	echo "Collecting garbage"
-	nix-store --gc --print-roots | egrep -v "^(/nix/var|/run/\w+-system|\{memory|/proc)"
-}
-
-##    store-optimise    Optimise nix-store
-function store-optimise {
-	echo "Optimizing nix-store. This may take a moment..."
-	nix-store --optimise
-}
-
-##    search PACKAGE    Search for package
-function search {
-	nix search nixpkgs $1
-}
-
-##
-## ~> Shell
-##
-
-##    shell NAME        Run a nix-shell from ./shell/
 function shell {
-	nix-shell ./shell/$1.nix
+	function run {
+		nix-shell ./shell/$1.nix
+	}
+	${@}
 }
 
 ${@:-info}