Access Control Lists( (ACLs) are a way to assign fine tuned permissions in Linux apart from using the chmod command. When the chmod command is used only one owner and one group can be assigned permissions on a file or directory. If multiple users need access to a resource we need to place them in a group and then give that group the necessary permissions. But with File ACLs in Linux we can assign fine grained permissions to each user and group on a file and even deny access to a particular user even if the file has world permissions. This tutorial on Linux File ACL will explain the usage of the commands getfacl and setfacl.Continue Reading…

A very useful Linux tip on how to make files and directories undeletable even by the root user. You can apply this tip on all important configuration files so that no one accidentally or intentionally deletes it. To achieve this the chattr (Change Attribute) command is used it Linux. The chattr command “immunizes” the file not only from deletion but also modification. The chattr command does care about chmod values, even if a file has 777 permissions immunizing the file will prevent it from being deleted or modified.Continue Reading…