Operating Systems and How Applications Work
- To run any application OS creates a Process.
- Each Process gets cpu share, Memory and Disk and Network based on the process which you are running.
- Each Process will have unique identifier (id)
Command Line
- Every Command is a computer program/Executable
- Commands have two types of arguments by the way you pass the values
- positional argument: This argument is processed based on position
cp 1.txt 2.txt
cp 3.txt 1.txt
- keyword argument: In this case around the argument you will pass a name or a keyword. Generally linux style name arguments have two hyphens
--
if you pass the keyword an single -
if you pass the shorthand notation
ping -c 2 google.com
ping google.com -c 2
ping --count 2 google.com
- Every command line generally has a documentation which we call as manual. Lets start using manual to figure out what commands can do
- When you type any command every operating system has a location where the folders to be searched are configured. This is done by a variable (Environmental variable) called as PATH
Approach to work with commands
- What does the command do.
- Use
--help
or man <command>

- Google
<command> examples

Concept of user and home directory
- When a user is created in any system a directory called as home directory will be created for the user where he has full permissions
- Tilde
~
on a terminal represents home directory
Windows: C:\Users\<username>
Linux: /home/<username>
Mac: /Users/<username>
- In command line dot
.
represents current directory and double dots ..
represent parent directory
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