Hi, I have a directory that needs to be accessed by the members of two groups:

group1 needs rw access
group2 needs only r access
others should have no rights

I must be missing something obvious, but I can't figure out how to do it! Any ideas?

This is one of the major limitations of the standard Unix file permissions system. The only way I know of to achieve this using just one directory is to use ACLs (access control lists, see man getfacl/setfacl), but unfortunately these are not supported by all filesystems, or by all OS's and/or utilities... e.g. some backup software will not back them up.

This is unfortunate because they are very useful for some other things, such as setting default permissions on files and subdirectories created in the directory.

One other option you have is to use a structure like this:

drwxr-x--- user1 group2 topdir
   drwxrwsr-x user1 group1 subdir
       -rw-r--r-- user1 group1 files

Thanks Annihilannic, your solution is clever!