To change the attributes (permissions) of a file or folder, use the chmod command:
chmod new_permission filename
Example (see how the attributes of the ubuntu.jpg file changed from 640 to 777):
chmod 777 ubuntu.jpg
ls -l
-rwxrwxrwx 1 mvps mvps 37126 Jun 25 03:15 ubuntu.jpg
Protecting files with chmod
Changing the owner of a file
This can be very simple to do from the terminal using the chown command:
chown new_username:default_group_new_username filename
or (to keep in mind that the dot character ‘.’ after the new user name, automatically adds that user’s default group)
chown new_username. filename