Environment Variables in Linux

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