This command allows you to make a previously available file system unavailable for mounting by clients. You can use the unshare command to unshare any file system—whether the file system was shared explicitly with the share command or automatically through /etc/dfs/dfstab. If you use the unshare command to unshare a file system that you shared through the dfstab file, be careful. Remember that the file system is shared again when you exit and reenter run level 3. You must remove the entry for this file system from the dfstab file if the change is to continue.
When you unshare an NFS file system, access from clients with existing mounts is inhibited. The file system might still be mounted on the client, but the files are not accessible.
This command unshares a specific file system:
# unshare /usr/src