Working in the shell

Let's get started by opening the Terminal, and we will familiarize ourselves with the bash shell environment:

1. Open the Linux Terminal and type in:

    $ echo $SHELL
    /bin/bash
  

1. The preceding output in the Terminal says that the current shell is /bin/bash, such as the Bash shell:

    $ bash -version
    GNU bash, version 4.3.48(1)-release (x86_64-pc-linux-gnu)
    Copyright (C) 2013 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html


    This is free software; you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.
  

Hereafter, we will use the word Shell to signify the Bash shell only. If we intend to use any other shell, then it will be specifically mentioned by name, such as KORN and other similar shells.

In Linux, filenames in lowercase and uppercase are different; for example, the files Hello and hello are two distinct files. This is unlike Windows, where case does
not matter.

As far as possible, avoid using spaces in filenames or directory names such as:

• Wrong filename—Hello World.txt
• Correct filename—Hello_World.txt or HelloWorld.txt

This will make certain utilities or commands fail or not work as expected, for example, the make utility.

While typing in filenames or directory names of the existing files or folders, use the tab completion feature of Linux. This will make working with Linux faster.