file("/tmp/script","w").write(script)
-p = subprocess.Popen(["ssh", "-A", hostname], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
-enctext = p.communicate(input=script)[0]
+p = subprocess.Popen(["ssh", "-A", hostname], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+(enctext,stderr) = p.communicate(input=script)
+
+if stderr:
+ print >> sys.stderr, stderr
+
+if "No such file" in stderr:
+ sys.exit(-1)
enctext = enctext.split("START")[1]