twisted.internet.reactor.spawnProcess raises OSError(13, 'Permission denied')

When I try running a python script via `twisted.internet开发者_C百科.reactor.spawnProcess':

from twisted.internet import protocol, reactor

class ProcessProtocol(protocol.ProcessProtocol):
    def connectionMade(self):
        self.transport.closeStdin()

    def childDataReceived(self, childFD, data):
        print data

def main():
    proto = ProcessProtocol()
    cmd = ['/var/projects/python/worker.py']
    reactor.spawnProcess(proto, cmd[0], cmd)

if __name__ == "__main__":
    exit(main())

I get the following error:

Upon execvpe /var/projects/python/worker.py ['/var/projects/python/worker.py', '5'] in environment id 29011152
:Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/Twisted-11.0.0-py2.6-linux-x86_64.egg/twisted/internet/process.py", line 414, in _fork
    executable, args, environment)
  File "/usr/local/lib/python2.6/dist-packages/Twisted-11.0.0-py2.6-linux-x86_64.egg/twisted/internet/process.py", line 460, in _execChild
    os.execvpe(executable, args, environment)
  File "/usr/lib/python2.6/os.py", line 353, in execvpe
    _execvpe(file, args, env)
  File "/usr/lib/python2.6/os.py", line 368, in _execvpe
    func(file, *argrest)
OSError: [Errno 13] Permission denied

---

You might not have the permission to execute '/var/projects/python/worker.py', or that script's execute bit is not set. Do an ls -l /var/projects/python/worker.py and check it?