I have a shared hosting account with justhost, what i need is to give an FTP access to a site operator, to his website.
The website is a sub-folder under the www folder.
I know how to limit his FTP access to the folder only, but i need a way to isolate the files that he will upload as well, to prevent a script from accessing the parent folders ETC.
is there any way to do it?
As often, it depends...
You can't really prevent the site operator from uploading badly written scripts or even malicious scripts unless you create something like a staging area and have somebody do a code revision before publication on the webserver itself.
Since often that's not feasable, you can configure your webserver to be very restrictive with the content in that website, effectively you'll only allow static content: