Book Image

Learn Linux Quickly

By : Ahmed AlKabary
Book Image

Learn Linux Quickly

By: Ahmed AlKabary

Overview of this book

Linux is one of the most sought-after skills in the IT industry, with jobs involving Linux being increasingly in demand. Linux is by far the most popular operating system deployed in both public and private clouds; it is the processing power behind the majority of IoT and embedded devices. Do you use a mobile device that runs on Android? Even Android is a Linux distribution. This Linux book is a practical guide that lets you explore the power of the Linux command-line interface. Starting with the history of Linux, you'll quickly progress to the Linux filesystem hierarchy and learn a variety of basic Linux commands. You'll then understand how to make use of the extensive Linux documentation and help tools. The book shows you how to manage users and groups and takes you through the process of installing and managing software on Linux systems. As you advance, you'll discover how you can interact with Linux processes and troubleshoot network problems before learning the art of writing bash scripts and automating administrative tasks with Cron jobs. In addition to this, you'll get to create your own Linux commands and analyze various disk management techniques. By the end of this book, you'll have gained the Linux skills required to become an efficient Linux system administrator and be able to manage and work productively on Linux systems.
Table of Contents (24 chapters)

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...