EM.system can take multiple arguments for the command

lib/em/processes.rb

@@ -109,6 +109,9 @@ def EventMachine::system cmd, *args, &cb
     cb ||= args.pop if args.last.is_a? Proc
     init = args.pop if args.last.is_a? Proc
 
+    # merge remaining arguments into the command
+    cmd = ([cmd] + args.map{|a|a.to_s.dump}).join(' ')
+
     EM.get_subprocess_pid(EM.popen(cmd, SystemCmd, cb) do |c|
       init[c] if init
     end.signature)

tests/test_processes.rb

@@ -99,6 +99,30 @@ def test_em_system_with_two_procs
       })
     }
 
-    assert_equal($out, "hello\n")
+    assert_equal("hello\n", $out)
+  end
+
+  def test_em_system_cmd_arguments
+    EM.run{
+      EM.system('sh', '--version', proc{ |process|
+      }, proc{ |out,status|
+        $out = out
+        $status = status
+        EM.stop
+      })
+    }
+
+    assert_match(/version/i, $out)
+  end
+
+  def test_em_system_spaced_arguments
+    EM.run{
+      EM.system('ruby', '-e', 'puts "hello"', proc{ |out,status|
+        $out = out
+        EM.stop
+      })
+    }
+
+    assert_equal("hello\n", $out)
   end
 end