vmux - Cloud Compute in 5 Seconds

Run any command in the cloud. Close your laptop, keep running.

Setup

vmux whoami  # Check login status
vmux login   # If needed

vmux run

vmux run [flags] <command>

Flags

Flag Combinations

Flags can be combined: -dp 8000 = detached + port 8000

vmux run python script.py           # Streams logs, blocks
vmux run -d python script.py        # Detached, returns job ID
vmux run -p 8000 python server.py   # Expose port 8000, get preview URL
vmux run -dp 8000 python server.py  # Detached + port (most common for web)
vmux run -d --preview bun run dev   # Auto-detect port from framework
vmux run -p 3000 -p 8000 npm run dev  # Multiple ports
vmux run -e API_KEY=xxx python app.py # With env var

JSON Mode (for LLMs/agents)

vmux run --json -d python server.py
# Returns: {"job_id": "...", "preview_urls": {...}}

After Deploy

Always give the user:

1. The preview URL (if port exposed) - format: https://<port>-<job-id>-<token>.purr.ge
2. The job ID
3. How to monitor: vmux logs -f <job-id>
4. How to stop: vmux stop <job-id>

Other Commands

vmux ps                 # List running jobs
vmux logs <job-id>              # All logs
vmux logs -f <job-id>           # Follow logs in real-time
vmux logs --tail 50 <job-id>    # Last 50 lines
vmux logs -f --tail 50 <job-id> # Last 50, then follow
vmux logs --json <job-id>       # JSON output for agents
vmux logs --json --tail 20 <job-id>  # Last 20 lines as JSON
vmux exec <job-id> <cmd>                        # Run command in running job (stateful shell)
vmux exec <job-id> --file SRC[:DST] <cmd>       # Upload local file(s) into the job, then exec
vmux exec --json <job-id> <cmd>                 # JSON output
vmux exec --create <cmd>                        # Auto-create Modal sandbox, run command
vmux exec --create --provider cloudflare <cmd>  # Auto-create Cloudflare sandbox
vmux exec --create --gpu H100 <cmd>             # Modal with GPU
vmux attach <job-id>    # Interactive tmux session (Ctrl+B,D to detach)
vmux stop <job-id>      # Kill job
vmux stop -a            # Stop all running jobs
vmux debug <job-id>     # Show tmux status and processes
vmux secret set KEY     # Store secret in keychain

Agent Workflow

For LLM/agent automation, use --json flags:

# Option A: Start job explicitly, then exec
vmux run --json -d -p 8000 python server.py
# Returns: {"job_id": "abc123", "preview_urls": {"8000": "https://..."}}

# Option B: Auto-create sandbox with exec --create
vmux exec --json --create --gpu H100 "pip install torch"
# Returns: {"job_id": "abc123", "stdout": "...", "exit_code": 0}

# Check logs (last 20 lines)
vmux logs --json --tail 20 abc123
# Returns: {"logs": "...", "lines": 20}

# Execute more commands (reuse job_id, stateful shell)
vmux exec --json abc123 "python train.py"
# Returns: {"job_id": "abc123", "stdout": "...", "exit_code": 0}

# Stop when done
vmux stop abc123

Empty Sandbox (for interactive use)

# Provision empty sandbox (persistent until stopped)
vmux run -d sleep infinity                    # Cloudflare
vmux run -d --provider modal --gpu H100 sleep infinity  # Modal + GPU

# Or use exec --create (provisions + runs command in one step)
vmux exec --create "pip install torch"                    # Modal (default)
vmux exec --create --provider cloudflare "apt install -y curl"  # Cloudflare
vmux exec --create --gpu H100 "pip install torch"         # Modal + GPU

Upload Local Files Into a Job

Use vmux exec --file to upload local scripts/configs into a running job (works on both Cloudflare and Modal providers):

vmux exec <job-id> --file ./prepare.py python /workspace/prepare.py
vmux exec <job-id> --file ./cfg.json:/workspace/cfg.json python train.py --config /workspace/cfg.json

Monitoring Long-Running Commands

Important: vmux exec is non-streaming. For tailing logs:

Option 1: Pipe to stdout + vmux logs (Recommended)

Run training with output to stdout:

vmux exec <job-id> "python -u train.py 2>&1 | tee -a train.log"

Then stream via:

vmux logs -f <job-id>

Option 2: Poll log files

For file-based logs, poll periodically:

vmux exec <job-id> "tail -n 50 train.log"

Option 3: Inspect Files via exec

vmux exec <job-id> "tail -n 50 /workspace/train.log"

Option 4: Attach for interactive tailing

vmux attach <job-id>
# Inside tmux:
tail -f train.log
# Ctrl+B,D to detach