How to detect whether file uploaded by FTP

Question

I have a client who uploads an XML file to a directory on my server using a third party script over which I have no control. Upon upload the file gets processed by a php script.

I have a cronjob which checks the dir every hour to see whether a file has been uploaded but if the upload takes place at, say, 3:01pm it won't be processed until 4:00pm. My host forbids running a cronjob more frequently than once per hour.

Is there a way to detect and advise immmediately upon a file arriving?

Answer 1

make a file checker.sh , and run it in background ./checker.sh /dev/null 2>&1 & , or run it in screen

#!/bin/bash

COUNTER=0
while [  $COUNTER -lt 99999 ]; do

if [ -f "/path/to/your/file" ]; then
    #do action here ,run a  script a program etc #the file is there
fi

sleep 5
let COUNTER=COUNTER+1 

done

Answer 2

The short answer is yes, it is possible to detect a file upload and perform an immediate action. However, this is not what I would call a "simple" solution. You would want to set up some sort of daemon so that you can run PHP continually (or use a different language entirely to monitor for the file).

The simple solution is to lower your cron interval, and then just add some kind of anti-stacking mechanic (like a lockfile) to ensure your script doesn't execute if it's already running.

Answer 3

If you are running Linux you could look at the inotifywait command which is part of the inotify-tools package. This can be set up to wait until a file is created in a particular directory as follows:

#!/bin/bash
while true
do
inotifywait -e create /home/myuser/upload_dir/ && php /home/myuser/scripts/process_file.php
done