An operating system is the primary software that manages all the hardware and other software on a computer. The operating system, also known as an “OS”, interfaces with the computer’s hardware and provides services that applications can use.
- Linux
- Windows
- macOS (Based on UNIX)
- 1971 - UNIX first release
- 1981 - MS-DOS first release
- 1994 - Linux first release
- Laptops
- Desktops
- Smartphones
- Raspberry pi
- Datacenters
- etc.
- 32 bits - x86
- 64 bits - x64
- arm
- more about it here
We will focus on Linux in this course, mainly Ubuntu because it is stable, open source, fairly small and fast.
If you are really confortable with Linux feel free to use centOS, Fedora or any other distro you'd like just be careful with Arch.
In 1991, at the university of Helsinki, Finland, a 23 year old computer science student purchased his personal computer. It came with an operating system called MS-DOS.
But he wasn't satisfied with it. He preferred using UNIX - the operating system he used at his university. So he went to buy UNIX for his personal use. The least expensive UNIX he could buy was $5000. (which is $9412 in today's rate!). That student was none other than Linus Torvalds.
And that day he decided to create a brand new, from scratch, free UNIX-like operating system - LINUX. And along with help from 100 other developers released its first version in 1994.
Fast-forward to 2020, LINUX now powers
- All of top 500 fastest super computers in the world
- 96.3% of the top 1 million web servers.
- And 86% of all smartphones in the world (probably includes yours Android, chromeOS...)
- And also, Linux and DevOps tools have a close relationship.
- Tools like Docker and Ansible were developed in Linux first.
- Permissions
-
Folder structure
-
Commands
- Print it an put on your mirror, or your desk this is your new guide! :)
- Print it an put on your mirror, or your desk this is your new guide! :)
- Ubuntu
- CentOS
- Red Hat
- Suse
- Debian
- Fedora
- etc.
- What is the shell?
TL;DR: The shell is a program that takes commands from the keyboard and gives them to the operating system to perform
- Go to your linux VM
- Create a folder called practicing-scripts
- Create a file called hello_world:
touch hello_world - Put this content
#!/bin/bash
# My first script
echo "Hello World!"- Run the script:
./hello_world
You should receive an error:
-bash: ./hello_world: Permission deniedThis means our script does not have execution permission (the x) part of the permissions. let's set it.
- Set permissions for the script:
chmod 755 hello_world - Run the script again:
./hello_world
Hello World!There you go, you did it!!!
- What does the first line means?
- The first line of the script is important. This is a special clue, called a shebang, given to the shell indicating what program is used to interpret the script. In this case, it is /bin/bash. Other scripting languages such as Perl, awk, tcl, Tk, and python also use this mechanism.
- Are extensions mandatory?
- How can I convert my script to a "program like" execution?
- Do I need to care about permissions all the time?
- I've seen echo in PHP, is it the same?
Let's first check all global execution places we have:
echo $PATH
Do you see the current directory in there?
pwd
Let's create a bin folder under my user
cd ~ & mkdir bin
What is this & sign ???
This is a sign that allows you to group commands
- Folder structure, create, delete folders recursively
- Shell scripts, the more the merrier
- Study the linux commands from the cheat sheet
- What does grep do?
- What does tail do?
- How can I create an alias?
- Try to version all your scripts using git. That way you will learn two things at once.
Resources
- Very cool site with lots of linux tips
- Linux commands website: http://linuxcommand.org/