Hands-On System Programming with Go

Read, write, and execute

Users and groups are used as the first two layers of protection for accessing a file. The user that owns a file has a set of permissions that differs from the file group. Whoever is not the owner and does not belong to the group has different permissions. These three sets of permissions are known as owner, group, and other.

For each element of the set there are three actions that may be carried out: reading, writing, and executing. This is very straightforward for files but it means something different for directories. Read makes it possible to list the contents, write is used to add new links inside, and execute is used to navigate it.

Three permissions are represented by an octal value, where the first bit is read ...