Read extern file and wait for changes in Python

Question

I want to read a file and when the file changed (i.e. for a external program), print the new information readed. Something like this:

import sys, os

with open('file.txt', 'r') as f:
    fid = f.fileno()
    r = os.fdopen(fid)
    while True:
        print r.read()

And when I do:

echo "Hello world!" > file.txt

The python script show:

> Hello world!

Many thanks.

EDITED: The solution:

time = os.path.getmtime('file.txt')
while True:
    if (time <> os.path.getmtime('file.txt')):
        with open('file.txt', 'r') as f:
            info = f.read()
            print "Readed: " + info
        time = os.path.getmtime('file.txt')

Look at this https://github.com/seb-m/pyinotify – Deck Dec 11 '13 at 12:09 — Deck, Dec 11 '13 at 12:09

M4rtini · Accepted Answer · 2013-12-11T12:21:43.727

1

Get file modified time, read if it increases from the old time.

import os
import time
fileName = 'test'
originalTime = os.path.getmtime(fileName)

while(True):
    if(os.path.getmtime(fileName) > originalTime):
        with open(fileName, 'r') as f:
            print "\n" + f.read(),
        originalTime = os.path.getmtime(fileName)
    time.sleep(0.1)

edited Dec 11 '13 at 12:21

answered Dec 11 '13 at 12:14

M4rtini

13,186
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Only works if the edit is appended on the old file. – M4rtini Dec 11 '13 at 12:15
A file could change without changing its size. – smeso Dec 11 '13 at 12:15
os.path.getmtime(file) get the file edited time with this, same principle without seeking to the originalsize – M4rtini Dec 11 '13 at 12:16
With os.path.getmtime works for me. It isn't very elegant, but works. Thanks. – Antonio Dec 11 '13 at 12:26

score 0 · Answer 2 · answered Dec 11 '13 at 12:13

0

Check Python watchdog. Python Watchdog quickstart

watchdog.events.FileModifiedEvent should do the trick.

answered Dec 11 '13 at 12:13

lipponen

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Read extern file and wait for changes in Python

2 Answers2