diff --git a/README.md b/README.md
index dc0a1e3..5967685 100644
--- a/README.md
+++ b/README.md
@@ -77,9 +77,8 @@ fn main() {
 ```
 
 ### Development
-If you don't want to install Rust itself, you can install [Docker], and run
-`$ ./dev`. This should bring up a temporary container from which you can run
-[cargo] commands.
+If you don't want to install Rust itself, you can run `$ ./dev` for a
+development CLI if you have [Docker] installed.
 
 ### License
 [MIT](https://github.com/dguo/strsim-rs/blob/master/LICENSE)
@@ -91,5 +90,3 @@ If you don't want to install Rust itself, you can install [Docker], and run
 [Hamming]:http://en.wikipedia.org/wiki/Hamming_distance
 [Optimal string alignment]:https://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance#Optimal_string_alignment_distance
 [Docker]:https://docs.docker.com/engine/installation/
-[cargo]:https://github.com/rust-lang/cargo
-
diff --git a/dev b/dev
index 6588873..4c85a49 100755
--- a/dev
+++ b/dev
@@ -1,13 +1,41 @@
-#!/usr/bin/env python
-
-from __future__ import print_function
+#!/usr/bin/env python3
+# ./dev --help
 
+import argparse
 import os
-from subprocess import call
+from subprocess import run
 import sys
 
-try:
-    call(['docker', 'run', '-it', '--rm', '-v', os.getcwd() + ':/src:cached',
-          '-w=/src', 'rust:1.20.0'])
-except OSError:
-    print('Please install Docker.', file=sys.stderr)
+parser = argparse.ArgumentParser(prog='./dev')
+subparsers = parser.add_subparsers(metavar='<command>', title='commands')
+command = [
+    'docker', 'run', '-it', '--rm', '-v', os.getcwd() + ':/src:cached',
+    '-w=/src', 'rust:1.21.0'
+]
+
+def cargo(args, remaining):
+    sys.exit(run(command + ['cargo'] + remaining or []).returncode)
+
+parser_cargo = subparsers.add_parser('cargo', help='run a cargo command')
+parser_cargo.set_defaults(func=cargo)
+
+def sh(args, remaining):
+    sys.exit(run(command + ['bash']).returncode)
+
+parser_sh = subparsers.add_parser('sh', help='bring up a shell')
+parser_sh.set_defaults(func=sh)
+
+def test(args, remaining):
+    sys.exit(run(command + ['cargo', 'test']).returncode)
+
+parser_test = subparsers.add_parser('test', help='run tests')
+parser_test.set_defaults(func=test)
+
+if len(sys.argv) > 1:
+    args, remaining = parser.parse_known_args()
+    try:
+        args.func(args, remaining)
+    except FileNotFoundError:
+        sys.exit('Please install Docker.')
+else:
+    parser.print_help()