diff --git a/lib/bin.js b/lib/bin.js
index 2badcbe..fd0e2b8 100755
--- a/lib/bin.js
+++ b/lib/bin.js
@@ -7,18 +7,29 @@ const spawn = require('@ahmadnassri/spawn-promise')
 
 let packages
 
+const argv = process.argv.slice(2)
+const group = argv.shift()
+
+// exit early
+if (!group) {
+  console.error('group required')
+  process.exit(1)
+}
+
 try {
-  packages = list(process.cwd(), process.argv[2])
+  packages = list(process.cwd(), group)
 } catch (err) {
-  console.log(err.message)
-  process.exit()
+  console.error(err.message)
+  process.exit(1)
 }
 
 if (packages.length === 0) {
   console.log('no packages')
-  process.exit()
+  process.exit(0)
 }
 
-spawn('npm', ['install', packages.join(' ')], { encoding: 'utf8' })
+const args = ['install', packages.join(' ')].concat(argv)
+
+spawn('npm', args, { encoding: 'utf8' })
   .then(streams => console.log(streams.stdout))
-  .catch(err => console.log(err.stderr))
+  .catch(err => console.error(err.stderr))