How can I create a new user that can only access a single directory with FTP on Ubuntu?

I’m not sure what your needs are, but I had a similar situation where I needed someone to be able to move files to/from my server. It turned out that it was a lot easier for me to use dropbox on my server and share it with them: https://www.dropbox.com/install?os=lnx

I don’t use ftp, but google is suggesting proftpd when I search.

The Filezilla server lets you establish what you share (directory level), with what accounts that’s shared, how it’s shared (read-only, read-write etc) and you can establish accounts within it that are ftp-only accounts. And it’s free !
I’m sure there are lots of nuts and bolts ways to accomplish the same thing but I found Filezilla easy for casual use.

Generally I believe you’d only give them access to their home directory and go from there.

This appears to have instructions for Ubuntu and setting up users

https://help.ubuntu.com/10.04/serverguide/C/ftp-server.html

linux admin is not my thing, but I brush up against it a lot. Linode could probably help you through their support system as this should be a common request there

Thanks guys! I will start looking.