Script to timestamp stdout and stderr from a process

timestamper.py

#!/usr/bin/env python2

from __future__ import print_function

import sys
import datetime
import time
from subprocess import Popen, PIPE
from Queue import Queue, Empty
from threading import Thread


def enqueue_output(out, queue, formatter):
	for line in iter(out.readline, b''):
		queue.put(formatter(line))
	out.close()

def format_line(line, prefix, timestamp=False):
	if timestamp:
		stamp = time.time()
	else:
		stamp = datetime.datetime.now()
	return "{}\t{}\t{}".format(prefix, stamp, line)

def print_output(queue, flush=False):
	try:
		while queue.qsize() > 0 or flush:
			lout = queue.get_nowait()
			dest = sys.stdout if lout.startswith("STDOUT") else sys.stderr
			print(lout, end='', file=dest)
	except Empty:
		pass

def start(timestamp, args):
	proc = Popen(args, stdin=sys.stdin, stdout=PIPE, stderr=PIPE, bufsize=1)
	q = Queue()
	tout = Thread(target=enqueue_output, args=(proc.stdout, q, lambda x: format_line(x, "STDOUT", timestamp)))
	terr = Thread(target=enqueue_output, args=(proc.stderr, q, lambda x: format_line(x, "STDERR", timestamp)))
	tout.daemon = True
	terr.daemon = True
	tout.start()
	terr.start()
	return (proc, q)

def main():
	argend = 0
	if "--" in sys.argv:
		argend = sys.argv.index("--")
	args = sys.argv[argend+1:]

	t = False
	for arg in sys.argv[1:argend]:
		if arg == "-t": t = True     # Print out UNIX timestamp
		elif arg == "-d": t = False  # Print out date + time string
		else:
			print("Unknown argument: {}".format(arg))
			return 1

	proc, q = start(t, args)
	ret = None
	while True:
		print_output(q)

		if proc.poll() is not None:
			ret = proc.returncode

		if ret is not None and proc.stdout.closed and proc.stderr.closed:
			break

	print_output(q, flush=True)
	return ret


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