Environment Variables in Linux

DerMeldos

Setting Environment Variables for Single Users

Method 1: Temporary Environment Variables
Temporary environment variables are defined within the current shell session and cease to exist once the shell terminates. To set a temporary environment variable, use the following syntax:

SSLKEYLOGFILE=/home/stanley/Documents/Coding/browser-log/sslkeylog.log

Method 2: Permanent Environment Variables for Single Users
Permanent environment variables persist across shell sessions and are available to the user who sets them. To set a permanent environment variable for a single user, use the export command followed by the variable definition:

export SSLKEYLOGFILE=/home/stanley/Documents/Coding/browser-log/sslkeylog.log

To make this permanent change effective, add the export command and variable definition to the user's initialization file. These files are typically located in the user's home directory:

~/.bashrc : For bash users
~/.zshrc : For zsh users
Open the appropriate file using a text editor like nano or vi. Add the export command followed by the variable definition to the end of the file. Save the file and exit the text editor. The next time the user logs in or opens a new terminal session, the permanent environment variable will be set.

Setting Environment Variables for All Users

Method 1: Permanent Environment Variables for All Users (Using Profile File)

Permanent environment variables for all users can be set by adding them to the /etc/profile file. This file is read by all users when they log in, so any changes made to the file will be reflected in the environment of all users.

Open the /etc/profile file in a text editor:

nano /etc/profile

Add the following line to the end of the file:

export SSLKEYLOGFILE=/home/stanley/Documents/Coding/browser-log/sslkeylog.log

Save the file and exit the text editor.
All users who log in after you make this change will have the SSLKEYLOGFILE environment variable set to /home/stanley/Documents/Coding/browser-log/sslkeylog.log.

Method 2: Permanent Environment Variables for All Users (Using Environment File)
Permanent environment variables for all users can alternatively be set by adding them to the /etc/environment file. This file is also read by all users when they log in, so any changes made to the file will be reflected in the environment of all users.

Open the /etc/environment file in a text editor:

nano /etc/environment

Add the following line to the end of the file:

export SSLKEYLOGFILE=/home/stanley/Documents/Coding/browser-log/sslkeylog.log

Save the file and exit the text editor.
All users who log in after you make this change will have the SSLKEYLOGFILE environment variable set to /home/stanley/Documents/Coding/browser-log/sslkeylog.log.

Verifying the Environment Variable
To verify that the environment variable has been set correctly, use the echo command followed by the variable name:

echo $SSLKEYLOGFILE

This command should display the specified path:

/home/stanley/Documents/Coding/browser-log/sslkeylog.log

DerMeldos

To see current environment variables type the following command:

root@SONARR0724:~# printenv

Output example:

SHELL=/bin/bash
LANGUAGE=en_US:en
PWD=/root
LOGNAME=root
XDG_SESSION_TYPE=tty
MOTD_SHOWN=pam
HOME=/root
LANG=en_US.UTF-8
SSH_CONNECTION=10.196.0.19 52023 10.73.0.178 22
XDG_SESSION_CLASS=user
TERM=xterm-256color
USER=root
SHLVL=1
XDG_SESSION_ID=191
XDG_RUNTIME_DIR=/run/user/0
SSH_CLIENT=10.196.0.19 52023 22
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus
SSH_TTY=/dev/pts/0
_=/usr/bin/printenv

To add a variable for this session only you can use "export"

root@SONARR0724:~# export NETBOX_HOST="https://netbox.rweigel.net"
root@SONARR0724:~# export ZABBIX_HOST="https://zabbix.rweigel.net"

To perma add them systemwide you need to add them to "/etc/environment"

nano /etc/environment

  GNU nano 7.2                                                                     /etc/environment                                                                              
ZABBIX_HOST="https://zabbix.rweigel.net"
NETBOX_HOST="https://netbox.rweigel.net"