sereyatiampati / alx-system_engineering-devops

CLI, Bash scripts, Shell Permissions and Redirections

0x00. Shell, basics

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 14.04 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 holberton-system_engineering-devops 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. Use this command: chmod u+x file. We will see later what it means.

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$ 

Author

• Sereya Tiampati - sereyatiampati