Introducing ACLs

In this section, we will give you a brief introduction to how ACLs, or access control lists, work.

Linux has some special file and folder permissions, namely the ACLs, setuid, setgid, and sticky bit. If you look at the file in the filesystem, such as a new file that only the root user has access to, currently we are logged in as olip:

As you can see, the olip user has no write access on that file. Maybe you have already asked yourself this question: how can you give permissions to a file or folder to individual users who are not the file or group owner, in our example root? The only way is to use the others group, but this is not individual as all users who are not the file or group owner fall into this category. But here, we want to set single user permissions; for example, for the olip user.

Access control lists, or ACLs, is a system that extends our normal...