Frequently Asked Question

How does chown work and why can only root change ownership?

chown changes the user and/or group that a file belongs to. chown alice file gives ownership to alice; chown alice:staff file sets both owner and group; chown :staff file changes only the group; chown -R alice:staff dir/ recurses into a tree. There is also a sibling tool chgrp that handles the group field on its own.

Only root can change a file's owner. The reason is historical and quotacentric: if any user could chown a file away, they could drop big files into a colleague's account to evade their own disk quota, or hand off a file to escape the audit trail. An ordinary user can change a file's group, but only if they own the file and are themselves a member of the target group, so you can move a file between groups you legitimately belong to but cannot launder it through groups you have no membership in.