Adding a string to an existing URL text file

[mickeykelley]

I want to add a string to an existing URL text file. I know I could GET the file from the URL, temporarily write it to the local HDD, add my string, then PUT the file back on the site, then finally delete the local temp file. However, I really want to avoid the step of having the file temporarily on the user HDD. Is there a way to just add a string to the bottom of an existing file on a web site?

What I am wanting to create is when the users register their program via the web , we capture the info (just a serial number, the date and time) to an existing file. I can then check and clear this file periodically from our site to know who has registered.