add bash ceru tool

ceru/subcmds/new/default.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+set -euo pipefail
+USAGE="${BOLD}${UNDERLINE}${RED}Usage${RESET}
+	${BOLD}${GREEN}$THIS new [option...] subcommand${RESET}
+
+${BOLD}${UNDERLINE}${RED}Options${RESET}
+	${BOLD}${MAGENTA}-h, --help${RESET}               Show this message (^_^)
+
+${BOLD}${UNDERLINE}${RED}Subcommands${RESET}
+	${BOLD}${CYAN}key${RESET}                      Generate a new binary-cache signing keypair"
+
+# parse all args
+SUBCMD=false # where a subcommand was specified
+while [[ $# -gt 0 ]]; do
+	ARG=$1
+	case $ARG in
+		-h|--help)
+			throw-usage 0 ;;
+		-*)
+			echo "[!] Unknown option \"$ARG\""
+			exit 1 ;;
+		*)
+			SUBCMD=true
+			break ;;
+	esac
+done; unset -v ARG
+
+# invalid usage occurs if no args or subcommand given
+if [[ $# = 0 || "$SUBCMD" = false ]]; then
+	throw-usage 1
+fi; unset -v SUBCMD
+
+# run provided subcommand
+run-subcmd "$@"