fix(commonjs): Keep the shebang at the top of the file content

packages/commonjs/src/index.js

@@ -271,7 +271,16 @@ export default function commonjs(options = {}) {
       // entry suffix is just appended to not mess up relative external resolution
       if (id.endsWith(ENTRY_SUFFIX)) {
         const acutalId = id.slice(0, -ENTRY_SUFFIX.length);
-        return getEntryProxy(acutalId, getDefaultIsModuleExports(acutalId), this.getModuleInfo);
+        const {
+          meta: { commonjs: commonjsMeta }
+        } = this.getModuleInfo(acutalId);
+        const shebang = commonjsMeta?.shebang ?? '';
+        return getEntryProxy(
+          acutalId,
+          getDefaultIsModuleExports(acutalId),
+          this.getModuleInfo,
+          shebang
+        );
       }
 
       if (isWrappedId(id, ES_IMPORT_SUFFIX)) {

packages/commonjs/src/proxies.js

@@ -44,7 +44,7 @@ export async function getStaticRequireProxy(id, requireReturnsDefault, loadModul
   return `export { default } from ${JSON.stringify(id)};`;
 }
 
-export function getEntryProxy(id, defaultIsModuleExports, getModuleInfo) {
+export function getEntryProxy(id, defaultIsModuleExports, getModuleInfo, shebang) {
   const {
     meta: { commonjs: commonjsMeta },
     hasDefaultExport
@@ -55,9 +55,13 @@ export function getEntryProxy(id, defaultIsModuleExports, getModuleInfo) {
     if (hasDefaultExport) {
       code += `export { default } from ${stringifiedId};`;
     }
-    return code;
+    return shebang + code;
   }
-  return getEsImportProxy(id, defaultIsModuleExports);
+  const result = getEsImportProxy(id, defaultIsModuleExports);
+  return {
+    ...result,
+    code: shebang + result.code
+  };
 }
 
 export function getEsImportProxy(id, defaultIsModuleExports) {

packages/commonjs/src/transform-commonjs.js

@@ -478,6 +478,13 @@ export default async function transformCommonjs(
     magicString.remove(0, commentEnd).trim();
   }
 
+  let shebang = '';
+  if (code.startsWith('#!')) {
+    const shebangEndPosition = code.indexOf('\n') + 1;
+    shebang = code.slice(0, shebangEndPosition);
+    magicString.remove(0, shebangEndPosition).trim();
+  }
+
   const exportMode = isEsModule
     ? 'none'
     : shouldWrap
@@ -561,13 +568,13 @@ function ${requireName} () {
 
   magicString
     .trim()
-    .prepend(leadingComment + importBlock)
+    .prepend(shebang + leadingComment + importBlock)
     .append(exportBlock);
 
   return {
     code: magicString.toString(),
     map: sourceMap ? magicString.generateMap() : null,
     syntheticNamedExports: isEsModule || usesRequireWrapper ? false : '__moduleExports',
-    meta: { commonjs: commonjsMeta }
+    meta: { commonjs: { ...commonjsMeta, shebang } }
   };
 }

packages/commonjs/test/fixtures/samples/shebang/main.js

@@ -0,0 +1,2 @@
+#!/usr/bin/env node
+module.exports = 1;

packages/commonjs/test/test.js

@@ -1291,3 +1291,18 @@ test('allows the config to be reused', async (t) => {
     ['bar.js']
   );
 });
+
+test('keep the shebang at the top of the file content', async (t) => {
+  const bundle = await rollup({
+    input: ['fixtures/samples/shebang/main.js'],
+    plugins: [commonjs()]
+  });
+
+  const { output } = await bundle.generate({
+    exports: 'auto',
+    format: 'cjs',
+    chunkFileNames: '[name].js'
+  });
+
+  t.is(output[0].code.startsWith('#!/usr/bin/env node\n'), true);
+});