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Chapter 8
A Crash Course in BashBog'liq linuxbasicsforhackers82
Chapter 8
A Crash Course in Bash
A shell is an interface between the user and the operating system that enables
you to manipulate files and run commands, utilities, programs, and much
more. The advantage of a shell is that you perform these tasks immediately
from the computer and not through an abstraction, like a GUI, which allows
you to customize your task to your needs. A number of different shells are
available for Linux, including the Korn shell, the Z shell, the C shell, and
the Bourne-again shell, more widely known as bash.
Because the bash shell is available on nearly all Linux and UNIX distri-
butions (including macOS and Kali), we’ll be using the bash shell, exclusively.
The bash shell can run any system commands, utilities, or applications
your usual command line can run, but it also includes some of its own built-
in commands. Table 8-1 later in the chapter gives you a reference to some
useful commands that reside within the bash shell.
In earlier chapters, you used the
cd
,
pwd
,
set
, and
umask
commands. In
this section, you will be using two more commands: the
echo
command, first
used in Chapter 7, which displays messages to the screen, and the
read
com-
mand, which reads in data and stores it somewhere else. Just learning these
two commands alone will enable you to build a simple but powerful tool.
You’ll need a text editor to create shell scripts. A text editor is a pro-
gram that can edit plain, unformatted text, like Notepad in Windows or
TextEdit in macOS. You can use whichever Linux text editor you like best.
Popular hacker choices include vi, vim, emacs, gedit, kate, and so on. I’ll be
using Leafpad in this book, as I have in previous chapters. Using a different
editor should not make any difference in your script or its functionality.
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