alx-system_engineering-devops

Shell essentials that will truly help software engineer!! Resources

Read or watch:

What Is “The Shell”?
Navigation
Looking Around
A Guided Tour
Manipulating Files
Working With Commands
Reading Man pages
Keyboard shortcuts for Bash
LTS
Shebang

man or help:

cd
ls
pwd
less
file
ln
cp
mv
rm
mkdir
type
which
help
man

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google: General

What does RTFM mean?
What is a Shebang

What is the Shell

What is the shell
What is the difference between a terminal and a shell
What is the shell prompt
How to use the history (the basics)

Navigation

What do the commands or built-ins cd, pwd, ls do
How to navigate the filesystem
What are the . and .. directories
What is the working directory, how to print it and how to change it
What is the root directory
What is the home directory, and how to go there
What is the difference between the root directory and the home directory of the user root
What are the characteristics of hidden files and how to list them
What does the command cd - do

Looking Around

What do the commands ls, less, file do
How do you use options and arguments with commands
Understand the ls long format and how to display it
A Guided Tour
What does the ln command do
What do you find in the most common/important directories
What is a symbolic link
What is a hard link
What is the difference between a hard link and a symbolic link

Manipulating Files

What do the commands cp, mv, rm, mkdir do
What are wildcards and how do they work
How to use wildcards

Working with Commands

What do type, which, help, man commands do
What are the different kinds of commands
What is an alias
When do you use the command help instead of man

Reading Man Pages

How to read a man page
What are man page sections
What are the section numbers for User commands, System calls and Library functions

Keyboard Shortcuts for Bash

Common shortcuts for Bash

LTS

What does LTS mean?

Requirements

General

Allowed editors: vi, vim, emacs
All your scripts will be tested on Ubuntu 20.04 LTS
All your scripts should be exactly two lines long ($ wc -l file should print 2)
All your files should end with a new line (why?)
The first line of all your files should be exactly #!/bin/bash
A README.md file at the root of the repo, containing a description of the repository
A README.md file, at the root of the folder of this project, describing what each script is doing
You are not allowed to use backticks, &&, || or ;
All your scripts must be executable. To make your file executable, use the chmod command: chmod u+x file. Later, we’ll learn more about how to utilize this command.

More Info

Example of line count and first line

julien@ubuntu:/tmp$ wc -l 12-file_type 2 12-file_type julien@ubuntu:/tmp$ head -n 1 12-file_type #!/bin/bash julien@ubuntu:/tmp$

In order to test your scripts, you will need to use this command: chmod u+x file. We will see later what does chmod mean and do, but you can have a look at man chmod if you are curious.

Example

julien@ubuntu:/tmp$ ls 12-file_type lll julien@ubuntu:/tmp$ ls -la lll -rw-rw-r-- 1 julien julien 15 Sep 19 21:05 lll julien@ubuntu:/tmp$ cat lll #!/bin/bash ls julien@ubuntu:/tmp$ ls -l lll -rw-rw-r-- 1 julien julien 15 Sep 19 21:05 lll julien@ubuntu:/tmp$ chmod u+x lll # you do not have to understand this yet julien@ubuntu:/tmp$ ls -l lll -rwxrw-r-- 1 julien julien 15 Sep 19 21:05 lll julien@ubuntu:/tmp$ ./lll 12-file_type lll julien@ubuntu:/tmp$

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