Writing to file during infinite while

Question

I need to write in a txt file during a infinite while. But it's not writing and if I don't use infinite while it's works. What do I have to change ? My goal is to ping different ip infinite time and when the ping fails, it's written in the file with the time and date

I've tried the code without the while True and it works. I think the code need to be stop to write but can we do without stop ?

import os
import datetime

fichier = open("log.txt", "a")
date = datetime.datetime.now()

hostnames = [
    '192.168.1.1',
    '192.168.1.2',
    '192.168.1.3',
]
while True :
    for hostname in hostnames:
        ping = os.system(" Ping " + str(hostname))
        if ping == 1:
            print("DOWN")
            fichier.write(str(date) + "    " + str(hostname) + '\n' + '\n')
        else:
            print("UP")

I expect the output when it's failed with a stamp Date/Time and the IP Address

see https://stackoverflow.com/questions/18048728/python-write-to-a-file-returns-empty-file, https://stackoverflow.com/questions/18984092/python-2-7-write-to-file-instantly — kostic017, Jan 09 '19 at 14:00
Possible duplicate of [Python write to a file returns empty file](https://stackoverflow.com/questions/18048728/python-write-to-a-file-returns-empty-file) — kvorobiev, Jan 09 '19 at 14:02
@kvorobiev not really. Cause is not about flushing the file. — Agapito Gallart Bernat, Jan 09 '19 at 14:24

Agapito Gallart Bernat · Accepted Answer · 2019-01-09T14:18:12.490

1

To sum up all the answers in one:

try:
 with open('log.txt', 'a') as fichier:
   while True:
       for hostname in hostnames:
           ping = os.system(" Ping " + str(hostname))
           if ping == 1:
           print("DOWN")
           fichier.flush()
           fichier.write(str(date) + "    " + str(hostname) + '\n' + '\n')
       else:
           print("UP")
except KeyboardInterrupt:
     print("Done!")

edited Jan 09 '19 at 14:18

answered Jan 09 '19 at 14:04

Agapito Gallart Bernat

343
2
11

This is not likely to behave any differently to the OP's current code. You are not flushing to the file. – roganjosh Jan 09 '19 at 14:15
That's better. Now we open and close file only once. Thanks for improving! – funnydman Jan 09 '19 at 14:15
1

@FUNNYDMAN but it doesn't flush the buffered writes – roganjosh Jan 09 '19 at 14:15
Thank's for the missing flush – Agapito Gallart Bernat Jan 09 '19 at 14:20

Writing to file during infinite while

1 Answers1