As a System Admin, our first priority will be to protect and secure data from unauthorized access. We all are aware of the permissions that we set using some helpful Linux commands like chmod, chown, chgrp… etc. However, these default permission sets have some limitation and sometimes may not work as per our needs. For example, we cannot set up different permission sets for different users on same directory or file. Thus, Access Control Lists (ACLs) were implemented.

Let’s say, you have three users, ‘tecmint1‘, ‘tecmint2‘ and ‘tecmint3‘. Each having common group say ‘acl’. User ‘tecmint1‘ want that only ‘tecmint2‘ user can read and access files owned by ‘tecmint1‘ and no one else should have any access on that.

ACLs (Access Control Lists) allows us doing the same trick. These ACLs allow us to grant permissions for a user, group and any group of any users which are not in the group list of a user.

Note: As per Redhat Product Documentation, it provides ACL support for ext3 file system and NFS exported file systems. 继续阅读 →