Updated: 28 September 2026 · Applies to: Ubuntu 24.04, Debian 12, AlmaLinux 9 and Rocky Linux 9
To give one user read and write access to a folder they do not own, use a group or an access control list (ACL). Example: user alice, folder /shares/project1/reports. Works on Ubuntu 24.04, Debian 12, AlmaLinux 9 and Rocky Linux 9.
Method 1: a shared group (simple, standard)
groupadd project1 usermod -aG project1 alice chgrp -R project1 /shares/project1/reports chmod -R g+rwX /shares/project1/reports chmod g+s /shares/project1/reports # new files get the group automatically
Alice must log out and in again for the new group to apply. Check with id alice.
Method 2: ACL (for one user, without changing groups)
setfacl -R -m u:alice:rwX /shares/project1/reports setfacl -R -d -m u:alice:rwX /shares/project1/reports # default ACL for new files getfacl /shares/project1/reports
A + at the end of the permissions in ls -l shows that an ACL is set. Remove it with setfacl -x u:alice /shares/project1/reports.
Note: Alice also needs execute (x) permission on every parent folder to reach the directory. If setfacl reports "Operation not supported", see "Solution for setfacl: “Operation not supported” in Linux Servers".
