Use ACLs in Linux

Let's suppose we have 2 groups: sales and account with 2 directories owned by respective users:

$ ls -l /data
total 0
drwxrwx---. 2 root account 6 Oct 12 19:30 account
drwxrwx---. 2 root sales   6 Oct 12 19:30 sales

To make group sales to access account directory:

$ setfacl -m d:g:sales:rx /data/account # this is setting the default permissions for new for files in the directory
$ setfacl -m g:sales:rx /data/account   # this one is for current directory files

To make group account to access sales directory

$ setfacl -m d:g:account:rx /data/sales
$ setfacl -m g:account:rx /data/sales

Get details about the directories:

$ getfacl /data/sales
$ getfacl /data/account