How to Manage Running Processes and Inspect System Resources in Ubuntu System Monitor

When an application freezes, a background script consumes 100% of your processor cycles, or your computer begins running sluggishly, diagnosing what is happening behind the desktop interface is essential. While seasoned Linux users frequently monitor processes via terminal utilities like htop, Ubuntu includes a comprehensive, graphical task manager called GNOME System Monitor. Mirroring the functionality of Windows Task Manager and macOS Activity Monitor, System Monitor lets you visualize resource consumption, identify memory leaks, and safely terminate unresponsive software with ease.

The Three Main Tabs of Ubuntu System Monitor

GNOME System Monitor classifies hardware and software diagnostics into three primary navigation views:

• Processes: A complete roster of every running desktop application, system daemon, and background thread, showing CPU percentage, memory allocation, and user permissions.
• Resources: Real-time dynamic visual line charts graphing CPU core load, physical RAM usage, swap space allocation, and network upload/download bandwidth.
• File Systems: Displays all mounted physical storage drives, root partitions, external USB disks, and total free/used disk capacity.

How to Open System Monitor in Ubuntu

Accessing System Monitor takes only a moment using standard Ubuntu shortcuts:

1. Press the Super (Windows) key on your keyboard to open the Activities search bar.
2. Type System Monitor and press Enter.
3. Alternatively, launch it from the terminal by running:

   gnome-system-monitor

4. The main System Monitor window will open displaying the Processes tab by default.

How to Identify and Terminate Frozen Applications

If an application becomes unresponsive and refuses to close through its window title bar:

1. In the Processes tab, use the search bar at the top right to filter by application name (e.g., firefox, gimp, or steam).
2. Click on the % CPU or Memory column header to sort descending, placing resource hogs at the top of the list.
3. Click on the unresponsive process to select it.
4. Click the red End Process button in the lower-right corner (or press Delete on your keyboard).
5. If the software remains stuck, right-click the process and choose Kill (sends SIGKILL signal 9), which forces the Linux kernel to terminate the program immediately and reclaim its memory.

Changing Process Priorities (Nice Values)

Linux allows you to adjust how aggressively the CPU scheduler allocates time slices to specific applications:

1. Right-click on any application process in the list.
2. Hover over Change Priority.
3. Choose between Very High, High, Normal, Low, or Very Low.
4. Lowering priority (higher “nice” value) on background tasks like video rendering or file archiving ensures your desktop remains fluid and responsive for web browsing.