I have a USB stick plugged into my Raspberry Pi for external storage, mostly to put music on for the Sockso Music Server to get at. But I wanted to use it a bit more for generic storage. FTP is great, you can get to it from any machine and the command line for it is the same on Win or Linux. So I can walk up to any machine, not have to install a thing and reach into a folder with FTP.
For instance, I have an infected Windows Machine, I don’t dare stick a USB stick in it. Instead I go to the command line, ftp to the Raspberry Pi and grab the tools I need from there.
The issue was that I tried to symlink from the ftp directory to the USB drive. vsFTP will not follow symlinks for security reasons.
Mount the directory you want under the FTP directory using bind. /media/sda is the USB stick mount point and the whole thing gets mounted under the FTP dir using…
sudo mount --bind /media/sda/ /home/ftpuser/usb-drive/