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)

Modifying user attributes

So we are not happy that the default shell for user tom is /bin/sh, and we want to change it to /bin/bash. We can use the usermod command to modify user attributes.

For example, to change the default shell for user tom to be /bin/bash, you can run the command usermod -s /bin/bash tom:

root@ubuntu-linux:~# usermod -s /bin/bash tom

Notice that you can also use the full name for the command option; so you can use --shell instead of -s. Anyways, let's see if we successfully changed the default shell for user tom:

root@ubuntu-linux:~# su - tom 
tom@ubuntu-linux:~$ whoami
tom
tom@ubuntu-linux:~$ echo $SHELL
/bin/bash

Great! We successfully did it. You can also change the UID of tom to 444 by running the command usermod -u 444 tom:

root@ubuntu-linux:~# usermod -u 444 tom

And we can indeed check that the UID of tom has changed by taking a peek at the /etc/passwd file:

root@ubuntu-linux:~# tail -n 2 /etc/passwd 
tom:x:444:1007::/home/tom:/bin/bash
jerry:x:777:1008:Jerry...