[Tutor] Subprocess.Popen process seems to be outputting to stdout even though redirected ?

[dave selby]

I have a simple script to tail a log file for an error string, it
works AOK but there is an unexpected side effect, when I run it in a
shell.

if I

echo "ERROR TEST" >> LOG

in a separate shell, I get the following from the script

ERROR TEST
GOT YA :)
ERROR TEST

So it looks like I am getting stdout from the tail -f, and two copies
of it ?, stdout should be piped to subprocess.stdout

tail = subprocess.Popen(['tail', '-f', LOG_FILE], shell=False,
stdout=subprocess.PIPE)

for out in iter(tail.stdout.readline, ''):

	out_str = out.rstrip('\n')

	if out_str.find('ERROR') != -1:
		print 'GOT YA :)'

	time.sleep(1)

Any ideas anyone ?

Cheers

Dave

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