Give write permissions to multiple users on a folder in Ubuntu

Question

There is a folder that is owned by user tomcat6:

drwxr-xr-x 2 tomcat6 tomcat6 69632 2011-05-06 03:43 document

I want to allow another user (ruser) write permissions on document folder. The two users (tomcat6 and ruser) does not belong to same group. I have tried using setfacl:

sudo setfacl -m  u:ruser:rwx document

but this gives me setfacl: document: Operation not supported error. Kindly help me.

Answer 1

There are two ways to do this: set the directory to "world" writable or create a new group for the two users and make the directory writeable to that group.

Obviously making it world writeable is a Bad Thing, so the second option is preferable.

Users in Linux can belong to more than one group. In this case you want to create a brand new group, let's call it tomandruser:

sudo groupadd tomandruser

Now that the group exists, add the two users to it:

sudo usermod -a -G tomandruser tomcat6
sudo usermod -a -G tomandruser ruser

Now all that's left is to set the permissions on the directory:

sudo chgrp -R tomandruser /path/to/the/directory
sudo chmod -R 770 /path/to/the/directory

Now only members of the tomandruser group can read, write, or execute anything within the directory. Note the -R argument to the chmod and chgrp commands: this tells them to recurse into every sub directory of the target directory and modify every file and directory it finds.

You may also want to change 770 to something like 774 if you want others to be able to read the files, 775 if you want others to read and execute the files, etc. Group assignment changes won't take effect until the users log out and back in.