Tip for setting $DISPLAY when connecting to a Linux machine.

Source: Dev.to

Background

I run an X server on my Windows machine and SSH into a Linux system.
Initially I manually set the DISPLAY variable to the Windows IP address and launched X clients such as xeyes, xclock, and xterm.
After creating an alias for xclock and putting the commands in a script, I still had to set DISPLAY each time I connected.

I discovered that the IP address of the client machine is stored in the SSH_CLIENT and SSH_CONNECTION environment variables. By extracting the first field of SSH_CLIENT I can obtain the IP address automatically.

Solution

1. Extract the client IP address from SSH_CLIENT.
2. Build a DISPLAY value (:0).
3. Export DISPLAY so X clients know where to render.
4. Add a fallback to localhost when not connected via SSH.
5. Place the logic in ~/.bashrc so it runs for every interactive login.

Example script (to put in ~/.bashrc)

# Get the client IP from SSH_CLIENT (if present)
host=$(echo "${SSH_CLIENT}" | cut -f1 -d' ')

# If not connected via SSH, default to localhost
if [ -z "$host" ]; then
    host=localhost
fi

# Build the DISPLAY variable and export it
export DISPLAY="${host}:0"

After adding this to ~/.bashrc, any new terminal session (including SSH logins) will have DISPLAY correctly set, allowing you to launch X clients without additional manual steps.