> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Manage system wide environment profiles
> This guide explains how to configure and maintain system-wide environment variables and login scripts for all users on a Linux system.
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`.
| Command | Description | Example Output |
| --------------- | ------------------------------------------------------------ | ----------------------- |
| `env` | Displays all environment variables | `PATH=/usr/local/bin:…` |
| `printenv HOME` | Shows the value of a specific variable (`HOME` in this case) | `/home/aaron` |
```bash theme={null}
# 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:
```bash theme={null}
# 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:
```bash theme={null}
$ 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`:
```bash theme={null}
$ sudo vim /etc/environment
```
Append lines in the format `KEY="value"`:
```text theme={null}
KodeKloud="https://www.kodekloud.com"
```
Save and log out, then back in to apply changes:
```bash theme={null}
$ echo $KodeKloud
https://www.kodekloud.com
```
The file `/etc/environment` only supports simple `KEY="value"` assignments. You cannot use shell expansions or commands here.
## 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:
```bash theme={null}
$ sudo vim /etc/profile.d/lastlogin.sh
```
Add:
```bash theme={null}
# 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`).
```bash theme={null}
# After logging out and back in
$ cat $HOME/lastlogin
Your last login was at: Thursday DEC 16 11:19:27 CDT 2021
```
Avoid syntax errors in `/etc/profile.d/` scripts. A malformed script can prevent users from logging in properly.
## Further Reading & References
* [Bash Manual: Environment](https://www.gnu.org/software/bash/manual/html_node/Environment.html)
* [Linux `env` Command](https://linux.die.net/man/1/env)
* [Filesystem Hierarchy Standard: /etc](https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s14.html)
***
In the next article, we’ll explore advanced shell initialization techniques, including per-shell configuration and custom prompts.