diff --git a/read-action-input b/read-action-input
index ff36b15..67c71c2 100755
--- a/read-action-input
+++ b/read-action-input
@@ -1,13 +1,11 @@
-#!/usr/bin/env node
-// helper script for printing kebab-cased env vars.
-// e.g., "foo-bar" -> "INPUT_FOO-BAR".
-//
-// This does not need to be implemented in nodejs,
-// but reimplementing this in sh is hard.
+#!/usr/bin/env bash
+# helper script for printing kebab-cased env vars.
+# e.g., "foo-bar" -> "INPUT_FOO-BAR".
+set -eu -o pipefail 
 
-const arg = process.argv[2]; // Equates to "$1" in sh
-const k = "INPUT_" + arg.toUpperCase();
-const v = process.env[k];
-if ( v !== undefined ) {
-  console.log(v);
-}
+arg=INPUT_${1^^}
+while IFS= read -r -d '' var; do
+  [[ $var = "$arg"=* ]] || continue
+  echo "${var#"${arg}="}"
+  break
+done </proc/self/environ