diff --git a/Makefile b/Makefile
index 84b9e46..2fdd36e 100644
--- a/Makefile
+++ b/Makefile
@@ -112,3 +112,6 @@ test-build-console-lib: build-dist sudo-install
 
 test-build-empty-app:
 	@bash tests/bare/build/empty-app-test.sh
+
+test-command:
+	@bash tests/bare/command-test.sh
diff --git a/bin/mush b/bin/mush
index 6cf4710..8836c41 100644
--- a/bin/mush
+++ b/bin/mush
@@ -35,7 +35,7 @@ legacy getoptions
 VERSION="Mush 0.1.0 (2023-09-07)"
 
 parser_definition() {
-  setup REST help:usage abbr:true -- "Shell's build system" ''
+  setup REST error:args_error help:usage abbr:true -- "Shell's build system" ''
 
   msg   -- 'USAGE:' "  ${2##*/} [OPTIONS] [SUBCOMMAND]" ''
 
@@ -56,6 +56,17 @@ parser_definition() {
   cmd   publish -- "Package and upload this package to the registry"
 }
 
+args_error() {
+  case "$2" in
+    notcmd)
+      console_error "no such command: '$3'\n\n        View all available commands with 'mush --help'"
+      ;;
+    *)
+      echo "ERROR: ($2) $1"
+  esac
+  exit 101
+}
+
 main() {
   #echo "ARGS: $@"
   #chmod +x target/debug/legacy/getoptions
diff --git a/src/main.sh b/src/main.sh
index 3e25603..266f015 100644
--- a/src/main.sh
+++ b/src/main.sh
@@ -14,7 +14,7 @@ legacy getoptions
 VERSION="Mush 0.1.0 (2023-09-07)"
 
 parser_definition() {
-  setup REST help:usage abbr:true -- "Shell's build system" ''
+  setup REST error:args_error help:usage abbr:true -- "Shell's build system" ''
 
   msg   -- 'USAGE:' "  ${2##*/} [OPTIONS] [SUBCOMMAND]" ''
 
@@ -35,6 +35,17 @@ parser_definition() {
   cmd   publish -- "Package and upload this package to the registry"
 }
 
+args_error() {
+  case "$2" in
+    notcmd)
+      console_error "no such command: '$3'\n\n\tView all available commands with 'mush --help'"
+      ;;
+    *)
+      echo "ERROR: ($2) $1"
+  esac
+  exit 101
+}
+
 main() {
   #echo "ARGS: $@"
   #chmod +x target/debug/legacy/getoptions
diff --git a/target/dist/mush b/target/dist/mush
index 6cf4710..8836c41 100644
--- a/target/dist/mush
+++ b/target/dist/mush
@@ -35,7 +35,7 @@ legacy getoptions
 VERSION="Mush 0.1.0 (2023-09-07)"
 
 parser_definition() {
-  setup REST help:usage abbr:true -- "Shell's build system" ''
+  setup REST error:args_error help:usage abbr:true -- "Shell's build system" ''
 
   msg   -- 'USAGE:' "  ${2##*/} [OPTIONS] [SUBCOMMAND]" ''
 
@@ -56,6 +56,17 @@ parser_definition() {
   cmd   publish -- "Package and upload this package to the registry"
 }
 
+args_error() {
+  case "$2" in
+    notcmd)
+      console_error "no such command: '$3'\n\n        View all available commands with 'mush --help'"
+      ;;
+    *)
+      echo "ERROR: ($2) $1"
+  esac
+  exit 101
+}
+
 main() {
   #echo "ARGS: $@"
   #chmod +x target/debug/legacy/getoptions
diff --git a/target/dist/mush.sh b/target/dist/mush.sh
index 6cf4710..8836c41 100644
--- a/target/dist/mush.sh
+++ b/target/dist/mush.sh
@@ -35,7 +35,7 @@ legacy getoptions
 VERSION="Mush 0.1.0 (2023-09-07)"
 
 parser_definition() {
-  setup REST help:usage abbr:true -- "Shell's build system" ''
+  setup REST error:args_error help:usage abbr:true -- "Shell's build system" ''
 
   msg   -- 'USAGE:' "  ${2##*/} [OPTIONS] [SUBCOMMAND]" ''
 
@@ -56,6 +56,17 @@ parser_definition() {
   cmd   publish -- "Package and upload this package to the registry"
 }
 
+args_error() {
+  case "$2" in
+    notcmd)
+      console_error "no such command: '$3'\n\n        View all available commands with 'mush --help'"
+      ;;
+    *)
+      echo "ERROR: ($2) $1"
+  esac
+  exit 101
+}
+
 main() {
   #echo "ARGS: $@"
   #chmod +x target/debug/legacy/getoptions
diff --git a/target/dist/mush.tmp b/target/dist/mush.tmp
index 6cf4710..8836c41 100755
--- a/target/dist/mush.tmp
+++ b/target/dist/mush.tmp
@@ -35,7 +35,7 @@ legacy getoptions
 VERSION="Mush 0.1.0 (2023-09-07)"
 
 parser_definition() {
-  setup REST help:usage abbr:true -- "Shell's build system" ''
+  setup REST error:args_error help:usage abbr:true -- "Shell's build system" ''
 
   msg   -- 'USAGE:' "  ${2##*/} [OPTIONS] [SUBCOMMAND]" ''
 
@@ -56,6 +56,17 @@ parser_definition() {
   cmd   publish -- "Package and upload this package to the registry"
 }
 
+args_error() {
+  case "$2" in
+    notcmd)
+      console_error "no such command: '$3'\n\n        View all available commands with 'mush --help'"
+      ;;
+    *)
+      echo "ERROR: ($2) $1"
+  esac
+  exit 101
+}
+
 main() {
   #echo "ARGS: $@"
   #chmod +x target/debug/legacy/getoptions
diff --git a/tests/bare/command-test.sh b/tests/bare/command-test.sh
new file mode 100644
index 0000000..c01ab38
--- /dev/null
+++ b/tests/bare/command-test.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+set -e
+
+echo "==> Build: mush"
+cp target/debug/mush target/debug/mush.sh
+bash target/debug/mush.sh build
+echo ""
+
+echo "==> Test: no such command"
+bash target/debug/mush.sh nosuchcommand