How to fire function on file upload to directory?

Question

Is their any way that whenever a user upload file via ftp a function fire automatically.I don't have any code.Search it on internet but not find any solution.

Answer 1

There is, and there is not - let me explain: When a user uploads a file via FTP, there are two players, who know about this fact:

• The FTP server software: It might or might not have a hook to notify a consumer
• The OS: It might or might not have such a facility

If you control the whole stack, i.e. OS, FTP-Server and your appliaction, you can quite easily do this, e.g. have inotify on Linux run a PHP interpreter. Be aware: This is not portable e.g. to some hosting site.

What seems to be a portable and mostly good enough way to do things is a polling loop:

• use e.g. PHP's flock facility to synchronize between concurrent requests
• have the winning (in the previous step) process update a file with the last change timestamp on the directory in question
• store the last seen such timestamp in your session, and on every request compare it to the current one: If they mismatch, you know at least something happened and can explore further.