computer-use

name	computer-use
description	Full desktop computer use for headless Linux servers. Xvfb + XFCE virtual desktop with xdotool automation. 17 actions (click, type, scroll, screenshot, drag, etc). Unlike OpenClaw's browser tool, operates at the X11 level so websites cannot detect automation. Includes VNC for live viewing.
version	1.2.1

Computer Use Skill

Full desktop GUI control for headless Linux servers. Creates a virtual display (Xvfb + XFCE) so you can run and control desktop applications on VPS/cloud instances without a physical monitor.

Environment

• Display: :99
• Resolution: 1024x768 (XGA, Anthropic recommended)
• Desktop: XFCE4 (minimal — xfwm4 + panel only)

Quick Setup

Run the setup script to install everything (systemd services, flicker-free VNC):

./scripts/setup-vnc.sh

This installs:

• Xvfb virtual display on :99
• Minimal XFCE desktop (xfwm4 + panel, no xfdesktop)
• x11vnc with stability flags
• noVNC for browser access

All services auto-start on boot and auto-restart on crash.

Actions Reference

Action	Script	Arguments	Description
screenshot	screenshot.sh	—	Capture screen → base64 PNG
cursor_position	cursor_position.sh	—	Get current mouse X,Y
mouse_move	mouse_move.sh	x y	Move mouse to coordinates
left_click	click.sh	x y left	Left click at coordinates
right_click	click.sh	x y right	Right click
middle_click	click.sh	x y middle	Middle click
double_click	click.sh	x y double	Double click
triple_click	click.sh	x y triple	Triple click (select line)
left_click_drag	drag.sh	x1 y1 x2 y2	Drag from start to end
left_mouse_down	mouse_down.sh	—	Press mouse button
left_mouse_up	mouse_up.sh	—	Release mouse button
type	type_text.sh	"text"	Type text (50 char chunks, 12ms delay)
key	key.sh	"combo"	Press key (Return, ctrl+c, alt+F4)
hold_key	hold_key.sh	"key" secs	Hold key for duration
scroll	scroll.sh	dir amt [x y]	Scroll up/down/left/right
wait	wait.sh	seconds	Wait then screenshot
zoom	zoom.sh	x1 y1 x2 y2	Cropped region screenshot

Usage Examples

export DISPLAY=:99

# Take screenshot
./scripts/screenshot.sh

# Click at coordinates
./scripts/click.sh 512 384 left

# Type text
./scripts/type_text.sh "Hello world"

# Press key combo
./scripts/key.sh "ctrl+s"

# Scroll down
./scripts/scroll.sh down 5

Workflow Pattern

1. Screenshot — Always start by seeing the screen
2. Analyze — Identify UI elements and coordinates
3. Act — Click, type, scroll
4. Screenshot — Verify result
5. Repeat

Tips

• Screen is 1024x768, origin (0,0) at top-left
• Click to focus before typing in text fields
• Use ctrl+End to jump to page bottom in browsers
• Most actions auto-screenshot after 2 sec delay
• Long text is chunked (50 chars) with 12ms keystroke delay

Live Desktop Viewing (VNC)

Watch the desktop in real-time via browser or VNC client.

Connect via Browser

# SSH tunnel (run on your local machine)
ssh -L 6080:localhost:6080 your-server

# Open in browser
http://localhost:6080/vnc.html

Connect via VNC Client

# SSH tunnel
ssh -L 5900:localhost:5900 your-server

# Connect VNC client to localhost:5900

SSH Config (recommended)

Add to ~/.ssh/config for automatic tunneling:

Host your-server
  HostName your.server.ip
  User your-user
  LocalForward 6080 127.0.0.1:6080
  LocalForward 5900 127.0.0.1:5900

Then just ssh your-server and VNC is available.

System Services

# Check status
systemctl status xvfb xfce-minimal x11vnc novnc

# Restart if needed
sudo systemctl restart xvfb xfce-minimal x11vnc novnc

Service Chain

xvfb → xfce-minimal → x11vnc → novnc

• xvfb: Virtual display :99 (1024x768x24)
• xfce-minimal: Watchdog that runs xfwm4+panel, kills xfdesktop
• x11vnc: VNC server with -noxdamage for stability
• novnc: WebSocket proxy with heartbeat for connection stability

Opening Applications

export DISPLAY=:99

# Chrome — only use --no-sandbox if the kernel lacks user namespace support.
# Check: cat /proc/sys/kernel/unprivileged_userns_clone
#   1 = sandbox works, do NOT use --no-sandbox
#   0 = sandbox fails, --no-sandbox required as fallback
# Using --no-sandbox when unnecessary causes instability and crashes.
if [ "$(cat /proc/sys/kernel/unprivileged_userns_clone 2>/dev/null)" = "0" ]; then
    google-chrome --no-sandbox &
else
    google-chrome &
fi

xfce4-terminal &                # Terminal
thunar &                        # File manager

Note: Snap browsers (Firefox, Chromium) have sandbox issues on headless servers. Use Chrome .deb instead:

wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo dpkg -i google-chrome-stable_current_amd64.deb
sudo apt-get install -f

Manual Setup

If you prefer manual setup instead of setup-vnc.sh:

# Install packages
sudo apt install -y xvfb xfce4 xfce4-terminal xdotool scrot imagemagick dbus-x11 x11vnc novnc websockify

# Run the setup script (generates systemd services, masks xfdesktop, starts everything)
./scripts/setup-vnc.sh

If you prefer fully manual setup, the setup-vnc.sh script generates all systemd service files inline -- read it for the exact service definitions.

Troubleshooting

VNC shows black screen

• Check if xfwm4 is running: pgrep xfwm4
• Restart desktop: sudo systemctl restart xfce-minimal

VNC flickering/flashing

• Ensure xfdesktop is masked (check /usr/bin/xfdesktop)
• xfdesktop causes flicker due to clear→draw cycles on Xvfb

VNC disconnects frequently

• Check noVNC has --heartbeat 30 flag
• Check x11vnc has -noxdamage flag

x11vnc crashes (SIGSEGV)

• Add -noxdamage -noxfixes flags
• The DAMAGE extension causes crashes on Xvfb

Requirements

Installed by setup-vnc.sh:

xvfb xfce4 xfce4-terminal xdotool scrot imagemagick dbus-x11 x11vnc novnc websockify