In my program I have to call an external program and parse its output. For that I use the os.popen2 function, and then read the output stream.
But the complexity is that the external program gives back its output in a piecemeal manner, with long delays between the outputs. In the main program I want to therefore read the output in a non-blocking manner, to read as many bytes as the child process is spitting out. The question is, how can I achieve that? I tried use select.select on the output stream returned by os.popen2, but it returns a readable file descriptor only after the whole child process ends. Here is a script simulating the external program: test.py: import sys, time print 'hello\n'*500 sys.stdout.flush() time.sleep(100) print 'world\n'*500 And here is what I am tring to do in the main program to read its output: import os, select cmd = 'python test.py' pin, pout = os.popen2(cmd) while not select.select([pout], [], [], some_timeout)[0]: pass pout.readline() I hope to get the first return very soon, before the external program sleeps, but instead only after the whole program exits do I get any output. Can anyone give me a hint? -- Hong Yuan 大管家网上建材超市 www.homemaster.cn -- http://mail.python.org/mailman/listinfo/python-list
