Manage system wide environment profiles

In this guide, you’ll learn how to configure and maintain environment variables and login scripts that apply to all users on a Linux system. We’ll cover:

• Understanding and viewing environment variables
• Persisting system-wide variables via /etc/environment
• Executing commands at login with /etc/profile.d/

Understanding Environment Variables

Environment variables are key–value pairs that shells and applications use to adjust behavior. You can list the current environment with either env or printenv.

# List all environment variables
$ env
PATH=/home/aaron/.local/bin:/home/aaron/bin:/usr/local/bin:/usr/bin
HISTSIZE=1000
GJS_DEBUG_TOPICS=JS ERROR;JS LOG
SESSION_MANAGER=local/unix:@tmp/.ICE-unix/2260

# Show HOME directory
$ printenv HOME
/home/aaron

To modify a variable for your current session, simply reassign it:

# Increase Bash history size for this session
$ HISTSIZE=2000
$ echo $HISTSIZE
2000

You can reference variables in scripts. For example, create a file in each user’s home directory:

$ touch "$HOME/saved_file"

This ensures the file lands in the right directory regardless of username.

Setting System-Wide Environment Variables

While individual users often tweak ~/.bashrc, you can enforce variables globally by editing /etc/environment:

$ sudo vim /etc/environment

Append lines in the format KEY="value":

KodeKloud="https://www.kodekloud.com"

Save and log out, then back in to apply changes:

$ echo $KodeKloud
https://www.kodekloud.com

Running Commands at Login

To execute scripts for every user at login, place them in /etc/profile.d/. For example, to record the last login timestamp:

$ sudo vim /etc/profile.d/lastlogin.sh

Add:

# Log the last login time into a file in the user’s home
echo "Your last login was at:" > "$HOME/lastlogin"
date                       >> "$HOME/lastlogin"

Scripts in /etc/profile.d/ are sourced by login shells automatically—you do not need a shebang (#!/bin/bash).

# After logging out and back in
$ cat $HOME/lastlogin
Your last login was at: Thursday DEC 16 11:19:27 CDT 2021

Further Reading & References

• Bash Manual: Environment
• Linux env Command
• Filesystem Hierarchy Standard: /etc

In the next article, we’ll explore advanced shell initialization techniques, including per-shell configuration and custom prompts.