I found myself wanting to create an extra FTP user for one of my Plesk machines that would only have access to a subdirectory of one of the machine’s domains.
It turns out this isn’t as tricky as I made it!
If you create a new OS user giving them the same user ID number as the primary FTP user and the Plesk group ‘psacln’, they have the same privileges. Giving them a home directory of the subdirectory instead of the primary user’s home directory chroots them inside it.. perfect.
1. Determine the uid number of the primary user (bob)
# cat /etc/passwd | grep bob
bob:x:10021:10001::/home/httpd/vhosts/bob.org:/bin/false
2. Create the new user with the same uid number, group, and shell (if you wish) but with a new home directory.
# useradd -u 10021 -o -d /home/httpd/vhosts/bob.org/httpdocs/bobs_subdir -g psacln -s /bin/false bob
# passwd bob
Give them a password and you’re done!
Thanks to this post on the SWSoft forums
http://forum.swsoft.com/showthread.php?postid=118777
