Verify platform inside command installer

src/atom.coffee

@@ -249,7 +249,6 @@ class Atom extends Model
 
   # Private: Call this method when establishing a real application window.
   startEditorWindow: ->
-    if process.platform is 'darwin'
     CommandInstaller = require './command-installer'
     CommandInstaller.installAtomCommand (error) -> console.warn error.message if error?
     CommandInstaller.installApmCommand (error) -> console.warn error.message if error?

src/command-installer.coffee

@@ -27,6 +27,8 @@ module.exports =
     "/usr/local/bin"
 
   install: (commandPath, callback) ->
+    return unless process.platform is 'darwin'
+
     commandName = path.basename(commandPath, path.extname(commandPath))
     directory = @getInstallDirectory()
     if fs.existsSync(directory)