He has a PhD in theoretical physics and perhaps soon another one in computing. He is the author of cfengine. Mark claims to be interested in everything and is into getting the most out of life. Nitro Media Inc. Access control lists, or ACLs, are notoriously awkward to maintain. Cfengine has begun a noninteractive approach to ACL management.
File permissions are the simplest and most basic security mechanism after passwords.
Traditionally in UNIX-like operating systems, a file has one owner, one group, and a set of access bits for the owner, members of the group, and others. This model is rather old, and, for many purposes, the scheme is not flexible enough. For ordinary users, it is inconvenient to have to define a group just to open a file to a single person. ACLs are extended file permissions. They allow you to open or close a file to a named list of users without having to create a special group.