diff -r 20051fe2a943 -r a21e9594307d core/src/luan/modules/Utils.java
--- a/core/src/luan/modules/Utils.java	Thu May 19 22:19:25 2016 -0600
+++ b/core/src/luan/modules/Utils.java	Fri May 20 17:03:57 2016 -0600
@@ -6,6 +6,7 @@
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.File;
+import java.io.InputStreamReader;
 import java.net.URL;
 import java.net.MalformedURLException;
 import luan.LuanException;
@@ -148,4 +149,51 @@
 		return toFile(path)!=null || toUrl(path)!=null;
 	}
 */
+
+
+
+
+	// process
+
+	public static class ProcessException extends IOException {
+		private ProcessException(String msg) {
+			super(msg);
+		}
+	}
+
+	public static void checkProcess(Process proc)
+		throws IOException
+	{
+		try {
+			proc.waitFor();
+		} catch(InterruptedException e) {
+			throw new RuntimeException(e);
+		}
+		int exitVal = proc.exitValue();
+		if( exitVal != 0 ) {
+			Reader err = new InputStreamReader(proc.getErrorStream());
+			String error = readAll(err);
+			err.close();
+			throw new ProcessException(error);
+		}
+	}
+
+	public static String getOutput(Process proc)
+		throws IOException
+	{
+		Reader in = new InputStreamReader(proc.getInputStream());
+		String s = readAll(in);
+		in.close();
+		return s;
+	}
+
+	public static String execProcess(String... cmd)
+		throws IOException
+	{
+		Process proc = Runtime.getRuntime().exec(cmd);
+		String s = getOutput(proc);
+		checkProcess(proc);
+		return s;
+	}
+
 }