run -> {deploy,lib/prelude.sh}

deploy

@@ -0,0 +1,15 @@
+#! /bin/sh
+#
+# usage: ./deploy CONFIG [[USER@]HOST]
+#
+set -euf
+
+. ./lib/prelude.sh
+
+user=root
+host=$1
+
+config=./$host.nix
+target=${2-$user@$host}
+
+verbose deploy "$config" "$target"

lib/prelude.sh

@@ -1,17 +1,3 @@
-#! /bin/sh
-set -euf
-
-main() {
-  case "$1" in
-    (deploy)
-      "$@"
-      ;;
-    (*)
-      echo "$0: unknown command: $1" >&2
-      exit 23
-  esac
-}
-
 # deploy : nixos-config x [user@]hostname -> ()
 deploy() {(
   main=$1
@@ -199,6 +185,8 @@ make_parent_dirs() {
   fi
 }
 
-if [ "${noexec-}" != 1 ]; then
-  main "$@"
-fi
+# verbose COMMAND [ARGS...]
+verbose() {
+  echo "$@" >&2
+  "$@"
+}