from __future__ import print_function from twisted.internet import utils, reactor def printTrueValue(val): print("/bin/true exits with rc=%d" % val) output = utils.getProcessValue('/bin/false') output.addCallback(printFalseValue) def printFalseValue(val): print("/bin/false exits with rc=%d" % val) reactor.stop() output = utils.getProcessValue('/bin/true') output.addCallback(printTrueValue) reactor.run()