Add the js2coffee executable.

bin/js2coffee

@@ -0,0 +1,7 @@
+#!/usr/bin/env coffee
+
+path = require('path')
+fs   = require('fs')
+lib  = path.join(path.dirname(fs.realpathSync(__filename)), '../lib')
+
+require(lib + '/command').run()

lib/command.coffee

@@ -1,13 +1,29 @@
 js2coffee = require('./js2coffee')
-_  = require('underscore')
-fs = require('fs')
+_    = require('underscore')
+fs   = require('fs')
+path = require('path')
 
-run = ->
-  files = process.argv.slice(2)
-  _.each files, (file) ->
-    contents = fs.readFileSync(file, 'utf-8')
-    output   = js2coffee.build(contents)
-    console.log output
+basename = path.basename
+cmd      = basename(process.argv[1])
 
-run()
+work = (fname) ->
+  contents = fs.readFileSync(fname, 'utf-8')
+  output   = js2coffee.build(contents)
+  console.log output
 
+module.exports =
+  run: ->
+    files = process.argv.slice(2)
+
+    try
+      work '/dev/stdin'
+
+    catch e
+      if files.length == 0
+        console.warn "Usage:"
+        console.warn "  #{cmd} file.js"
+        console.warn "  #{cmd} file.js > output.txt"
+        console.warn "  cat file.js | #{cmd}"
+        process.exit 1
+
+      _.each files, (fname) -> work fname