holberton-system_engineering-devops repository

This repository contains 28 projects:

• 0x00. Shell, basics
• 0x01. Shell, permissions
• 0x02. Shell, I/O Redirections and filters
• 0x03. Shell, init files, variables and expansions
• 0x04. Loops, conditions and parsing
• 0x05. Processes and signals
• 0x06. Regular expression
• 0x07. Networking basics #0
• 0x08. Networking basics #1
• 0x09. Web infrastructure design
• 0x0A. Configuration management
• 0x0B. SSH
• 0x0C. Web server
• 0x0D. Web stack debugging #0
• 0x0E. Web stack debugging #1
• 0x0F. Load balancer
• 0x10. HTTPS SSL
• 0x12. Web stack debugging #2
• 0x13. Firewall
• 0x14. MySQL
• 0x15. API
• 0x16. API advanced
• 0x17. Web stack debugging #3
• 0x18. Webstack monitoring
• 0x19. Postmortem
• 0x1A. Application server
• 0x1B. Web stack debugging #4
• Command line for the win (optional)

Learning Objectives

0x00. Shell, basics

• 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
• What do the commands ls, less, file do
• How to use options and arguments with commands
• Understand the ls long format and how to display it
• What does the ln command do
• What's found 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

0x01. Shell, permissions

• What do the commands chmod, sudo, su, chown, chgrp do
• Linux file permissions
• How to represent each of the three sets of permissions (owner, group, and other) as a single digit
• How to change permissions, owner and group of a file
• Why can’t a normal user chown a file
• How to run a command with root privileges
• How to change the user ID or become superuser
• Other Man Pages
• How to create a user
• How to create a group
• How to print real and effective user and group IDs
• How to print the groups a user is in
• How to print the effective userid

0x02. Shell, I/O Redirections and filters

• What the commands head, tail, find, wc, sort, uniq, grep, tr do
• How to redirect standard output to a file
• How to get standard input from a file instead of the keyboard
• How to send the output from one program to the input of another program
• How to combine commands and filters with redirections
• What are special characters
• Understand what do the white spaces, single quotes, double quotes, backslash, comment, pipe, command separator, tilde and how and when to use them

0x03. Shell, init files, variables and expansions

• What happens when you type ls -l *.txt
• What are the /etc/profile file and the /etc/profile.d directory
• What is the ~/.bashrc file
• What is the difference between a local and a global variable
• What is a reserved variable
• How to create, update and delete shell variables
• What are the roles of the following reserved variables: HOME, PATH, PS1
• What are special parameters
• What is the special parameter $?
• What is expansion and how to use them
• What is the difference between single and double quotes and how to use them properly
• How to do command substitution with $() and backticks
• How to perform arithmetic operations with the shell
• How to create an alias
• How to list aliases
• How to temporarily disable an alias
• How to execute commands from a file in the current shell

0x04. Loops, conditions and parsing

• How to create SSH keys
• What is the advantage of using #!/usr/bin/env bash over #!/bin/bash
• How to use while, until and for loops
• How to use if, else, elif and case condition statements
• How to use the cut command
• What are files and other comparison operators, and how to use them

0x05. Processes and signals

• What is a PID
• What is a process
• How to find a process’ PID
• How to kill a process
• What is a signal
• What are the 2 signals that cannot be ignored

0x06. Regular expression

• None

0x07. Networking basics #0

• OSI Model
  • What it is
  • How many layers it has
  • How it is organized
• What is a LAN
  • Typical usage
  • Typical geographical size
• What is a WAN
  • Typical usage
  • Typical geographical size
• What is the Internet
  • What is an IP address
  • What are the 2 types of IP address
  • What is localhost
  • What is a subnet
  • Why IPv6 was created
• TCP/UDP
  • What are the 2 mainly used data transfer protocols for IP (transfer level on the OSI schema)
  • What is the main difference between TCP and UDP
  • What is a port
  • Memorize SSH, HTTP and HTTPS port numbers
  • What tool/protocol is often used to check if a device is connected to a network

0x08. Networking basics #1

• What is localhost/127.0.0.1
• What is 0.0.0.0
• What is /etc/hosts
• How to display your machine’s active network interfaces

0x09. Web infrastructure design

• You must be able to draw a diagram covering the web stack you built with the sysadmin/devops track projects
• You must be able to explain what each component is doing
• You must be able to explain system redundancy
• Know all the mentioned acronyms: LAMP, SPOF, QPS

0x0A. Configuration management

• None

0x0B. SSH

• What is a server
• Where servers usually live
• What is SSH
• How to create an SSH RSA key pair
• How to connect to a remote host using an SSH RSA key pair
• The advantage of using #!/usr/bin/env bash instead of /bin/bash

0x0C. Web server

• What is the main role of a web server
• What is a child process
• Why web servers usually have a parent process and child processes
• What are the main HTTP requests
• What DNS stands for
• What is DNS main role

0x0D. Web stack debugging #0

• None

0x0E. Web stack debugging #1

• None

0x0F. Load balancer

• None

0x10. HTTPS SSL

• What is HTTPS SSL 2 main roles
• What is the purpose encrypting traffic
• What SSL termination means

0x12. Web stack debugging #2

• None

0x13. Firewall

• None

0x14. MySQL

• What is the main role of a database
• What is a database replica
• What is the purpose of a database replica
• Why database backups need to be stored in different physical locations
• What operation should you regularly perform to make sure that your database backup strategy actually works

0x15. API

• What is an API
• What is a REST API
• What are microservices
• What is the CSV format
• What is the JSON format
• Pythonic Package and module name style
• Pythonic Class name style
• Pythonic Variable name style
• Pythonic Function name style
• Pythonic Constant name style
• Significance of CapWords or CamelCase in Python

0x16. API advanced

• How to read API documentation to find the endpoints you’re looking for
• How to use an API with pagination
• How to parse JSON results from an API
• How to make a recursive API call
• How to sort a dictionary by value

0x17. Web stack debugging #3

• None

0x18. Webstack monitoring

• Why is monitoring needed
• What are the 2 main area of monitoring
• What are access logs for a web server (such as Nginx)
• What are error logs for a web server (such as Nginx)

0x19. Postmortem

• None

0x1A. Application server

• None

0x1B. Web stack debugging #4

• None

Command line for the win

• None