Shell Access

Clusters → ACE HPC Shell Access opens a fully functional bash terminal inside your browser. This gives you command-line access to the ACE HPC login node without needing an SSH client or key setup.

Screenshot note: A screenshot of the Shell Access terminal immediately after it opens, showing the bash prompt and the welcome/MOTD message.

Opening a Shell

1. In the navigation bar, click Clusters
2. Select ACE HPC Shell Access
3. A new browser tab opens with a black terminal window
4. After a few seconds the terminal connects and displays the bash prompt:

[username@kla-ac-hpc-login ~]$

You are now on the login node of ACE HPC, exactly as if you had SSH'd in.

What you can do from the shell

Everything you would normally do over SSH is available here:

• Load software modules: module load python/3.10
• Submit SLURM jobs: sbatch my_job.sh
• Check your queue: squeue -u $USER
• Cancel a job: scancel <job_id>
• Navigate and manage files: ls, cd, cp, rm, etc.
• Edit files: nano, vim, or emacs
• Check disk usage: df -h, du -sh ~/
• Run quick tests before submitting to the queue: python -c "import numpy; print(numpy.__version__)"

Copying and pasting

The in-browser terminal has slightly different clipboard behaviour depending on your operating system and browser:

OS	Copy	Paste
Linux	Select text with mouse (auto-copies)	Middle-click
macOS	Cmd + C	Cmd + V
Windows	Ctrl + C (after selecting)	Ctrl + V or right-click → Paste

If keyboard shortcuts do not work, right-click inside the terminal window for a context menu with copy/paste options.

Resizing the terminal

The terminal automatically fills the browser tab. If it appears too small, try:

• Zooming your browser out (Ctrl - or Cmd -)
• Dragging the browser window wider
• Running resize in the terminal to force it to re-read the window dimensions

Limitations compared to SSH

The browser-based shell works well for most tasks, but has a few limitations you should be aware of:

Limitation	Details
Interactive TUI programs	Programs like htop or tmux may behave unexpectedly or have rendering artefacts in some browsers
Session persistence	If your browser tab closes or your internet disconnects, the session ends and any foreground process is killed. Use tmux or screen to protect long-running processes
File transfer	You cannot drag-and-drop files into the terminal. Use the File Manager for transfers
X11 / GUI forwarding	Graphical applications launched from the terminal will not display. Use the Interactive Apps for GUI-based tools

Protect long-running commands with tmux

If you plan to run a command that takes more than a few minutes (such as building software or running a quick test), wrap it in a tmux session. This way, if your browser disconnects, the command continues running and you can re-attach later.

# Start a new tmux session
tmux new -s mysession

# Run your command
./configure && make install

# Detach safely (the process keeps running)
# Press Ctrl+B, then D

# Later, re-attach from any shell session
tmux attach -t mysession

When to use Shell Access vs SSH

Situation	Use
Quick file operations or job submission from any machine	Shell Access (OOD)
You need to transfer large files	SSH + scp/rsync
You need X11 forwarding for a GUI app	SSH with -X flag
You want persistent sessions you can reconnect to reliably	SSH + tmux/screen
You are behind a firewall blocking SSH port 22	Shell Access (OOD)