Understanding file permissions

In Linux, every file is assigned access permissions for three different entities; these entities are:

• The user owner of the file
• The group owner of the file
• Everyone else (also referred to as others/world)

We are already familiar with the user owner and the group owner; everyone else refers to any user on the system who is not the user owner and not the group owner.

You can think of these three entities like you, your friends, and everyone else. There are some things that you don't like to share with anyone, other things you like to share with your friends, and things you may like to share with everyone.

Each file has three types of access permissions:

• Read
• Write
• Execute

The meaning of each of these access permissions is not the same for files and directories. The following diagram explains the differences between access permissions for files versus directories:

Figure 5: File versus directory permissions

You can view the permissions of a file...