Log monitoring script

linux has a handy command called tail -f. I learned today that there is something called os.stat, so I wrote a little source. I am trying to monitor the file passed from the argument. It is realized only by moving to the end of the file, getting the current position of the file pointer, and reading the data from the file.

• I touched python for the first time in a long time.

sample.py

#-*- coding: utf-8 -*-
import time
import os
import sys
from stat import *

def usage():
	print "Usage: # python %s filename" % argv[0]
	quit()


def init(filename):
	file = open(filename,'r')

	#Move to the end of the file
	st_results = os.stat(filename)
	st_size = st_results[ST_SIZE]
	file.seek(st_size)

	return file

def tail_f(file, usec):
	msec = usec / 1000
	while 1:
		fpos = file.tell()
		line = file.readline()
		if not line:
			time.sleep(msec)
			file.seek(fpos)
		else:
			print line,
	#Not reached
	file.close()
	pass

if __name__ == '__main__':
	argv  = sys.argv
	argc  = len(argv)
	if( argc != 2 ):
		usage()

	filename = argv[1]
	file = init(filename)
	tail_f(file, 500)

By the way, if you only use it on linux, you can make it a wrapper script for tail -f.

sample.py

import sys
import os

if __name__ == '__main__':
	argv = sys.argv
	argc = len(argv)

	if argc != 2:
		print "test",
		quit()
	
	filename = argv[1]
	os.system('tail -f ' + filename )