Environment variables provide a way to influence software behavior on a system. They are dynamic named values that are set and used by processes. The printenv and env commands can be used to view environment variables. Environment variables are local to each process and child processes inherit the environment of their parent process, but changes made by the parent are not visible to the child. Environment variables are also case sensitive by convention and are typically named in uppercase. There are session-wide and system-wide environment variables that can be configured through various configuration files to make them persistent across sessions or the entire system.

1. Getting Started With Environment Variables in Linux...
Module 1:
What are environment variables?
- Set of dynamic named values
- They provide a way to influence the software behavior on a system
printenv and env commands ????
What are environment variables?What are environment variables?
- printenv - print all or part of environment
- env - run a program in a modified environment

2. Principles of Environment Variables …..
Module 2:
PROCESS LOCALITY ...
- The values of environment variables are local.
- These values are specific to the process in which or for which they
were set

3. Principles of Environment Variables …..
Module 3:
INHERITANCE...
- The Child process inherits (gets) all the environment variables from
parent with values
Note: Changes to env vars at run time by parent is not visible to child and vice versa
Process locality get applied here

4. Principles of Environment Variables …..
Module 4:
CASE SENSITIVITY...
- Env variables are case sensitive
- It is a common practice to name all env variables in English Capital
Letters and _ signs

5. Persistent Environment Variables (Session-wide Environment
Variables )...
Module 5:
Types:
- Session-wide Environment Variables
- System-wide Environment Variables
Session-wide Environment Variables
~/.pam_environment
~/.profile
Shell Config files
~/.bashrc
~/.bash_logout
~/.bash_history

6. Persistent Environment Variables (System-wide Environment
Variables )...
Module 6:
System-wide Environment Variables
- /etc/environment
- /etc/profile.d/*.sh
Other files:
-/etc/profile
-/etc/default/locale
-/etc/bash.bashrc