How to use the command 'quickemu' (with examples)

Quickemu is a versatile and efficient command-line tool designed to create and manage highly optimized desktop virtual machines (VMs) with remarkable speed. It simplifies the often complex process of setting up VMs, allowing users to quickly spin up virtual environments from pre-configured templates. This tool offers flexibility in managing VM states, configuring display and audio options, and even handling snapshots effectively. Whether you’re a developer, tester, or just an enthusiast exploring various operating systems, Quickemu streamlines your workflow with its powerful capabilities.

Use Case 1: Create and Run a Virtual Machine from a Configuration File

Code:

quickemu --vm path/to/file.conf

Motivation: This use case is highly beneficial when you need to set up and launch a virtual machine swiftly without delving into intricate configuration processes. By utilizing a pre-defined configuration file, users can maintain consistency across multiple setups and save time, making it ideal for both development and educational purposes.

Explanation:

• --vm: This argument specifies the path to the configuration file that contains the VM setup instructions. The file defines parameters such as the virtual hardware components and allocated system resources, streamlining the VM creation process.
• path/to/file.conf: This is a placeholder for the actual path to your configuration file, which holds all necessary details to create and run your VM.

Example Output: Upon executing the command, you would see a series of messages indicating the virtual machine is being created and subsequently launched, along with any feedback or errors related to the configuration settings.

Use Case 2: Do Not Commit Any Changes to Disk/Snapshot but Write Any Changes to Temporary Files

Code:

quickemu --status-quo --vm path/to/file.conf

Motivation: This option is perfect for testing scenarios where you need to evaluate software or system configurations without affecting the current VM state permanently. By using a temporary storage for changes, you ensure the original state remains unchanged regardless of what happens during your testing.

Explanation:

• --status-quo: This tells Quickemu to run the VM in a temporary mode where no changes are committed to disk, simulating a “snapshot” environment where all modifications are transient.
• --vm: As before, this is used to specify the virtual machine’s configuration file.
• path/to/file.conf: The actual path to the configuration file for the VM.

Example Output: The command outputs status messages as the VM loads, with notifications that the changes will not be committed to the disk, allowing for risk-free testing.

Use Case 3: Start the Virtual Machine in Full-Screen Mode and Select the Display Backend

Code:

quickemu --fullscreen --display sdl|gtk|spice|spice-app|none --vm path/to/file.conf

Motivation: Running a VM in full-screen mode enhances the user experience by emulating a native environment. Selecting a suitable display backend ensures optimal performance and compatibility with different host systems and user preferences, whether prioritizing performance or feature-rich interfaces.

Explanation:

• --fullscreen: Initiates the VM in full-screen mode, maximizing the usage of your screen estate for an immersive experience.
• --display sdl|gtk|spice|spice-app|none: Specifies the graphics backend to use. The available options cater to varying levels of performance and graphical features:
  • sdl: A simple, cross-platform backend ensuring broad compatibility.
  • gtk: Leverages GTK for potentially better integration with Linux desktops.
  • spice and spice-app: Provide enhanced graphical performance and remote computing capabilities.
  • none: Disables graphical output, useful for headless VMs.
• --vm: Points to the configuration file for the VM.
• path/to/file.conf: The configuration file path.

Example Output: The console displays initialization information, and the VM launches into full-screen mode with the chosen backend, allowing control over how graphics are rendered.

Use Case 4: Select a Virtual Audio Device to Emulate and Create a Desktop Shortcut

Code:

quickemu --sound-card intel-hda|ac97|es1370|sb16|none --shortcut --vm path/to/file.conf

Motivation: Audio configuration is pivotal in VMs aiming to replicate specific hardware environments or enabling full multimedia capabilities. Creating a desktop shortcut simplifies VM access for frequent use, enhancing convenience and productivity.

Explanation:

• --sound-card intel-hda|ac97|es1370|sb16|none: Determines the audio hardware to emulate, catering to different audio requirements and compatibility with varying guest OS expectations:
  • intel-hda: Provides high-definition audio.
  • ac97: A widely supported, older audio standard.
  • es1370, sb16: Legacy audio standards for specific compatibility cases.
  • none: Disables audio, useful for scenarios where sound is unnecessary.
• --shortcut: Automatically generates a shortcut on the desktop, enabling quick access to the VM.
• --vm: Specifies the configuration file path.
• path/to/file.conf: Path to the configuration file for the VM.

Example Output: Post-execution, users will see confirmation of the selected audio device and the creation of a desktop shortcut for immediate and easy VM access.

Use Case 5: Create a Snapshot

Code:

quickemu --snapshot create tag --vm path/to/file.conf

Motivation: Snapshots are vital in preserving the state of a VM at a particular point in time. This feature is incredibly useful for backup purposes, allowing users to revert to a specific state, ensuring peace of mind during experimental tasks or critical system updates.

Explanation:

• --snapshot create tag: This command tells Quickemu to create a snapshot, labeling it with the specified tag for easy reference and management, archiving the current VM state.
• --vm: Indicates the configuration file.
• path/to/file.conf: The configuration file for the VM in question.

Example Output: The system will acknowledge snapshot creation, displaying the saved tag, ensuring users can easily return to this VM state later.

Use Case 6: Restore a Snapshot

Code:

quickemu --snapshot apply tag --vm path/to/file.conf

Motivation: Restoring from a snapshot allows users to efficiently roll back a VM to a previous state, crucial for quickly undoing undesirable changes or recovering from software issues without a complete reinstallation.

Explanation:

• --snapshot apply tag: Restores the VM to the designated snapshot identified by the tag, effectively rolling back to a saved state.
• --vm: Specifies the VM’s configuration file path.
• path/to/file.conf: Path to the configuration file.

Example Output: After executing this command, the VM resets to the state saved under the given tag, confirming the snapshot restoration.

Use Case 7: Delete a Snapshot

Code:

quickemu --snapshot delete tag --vm path/to/file.conf

Motivation: Over time, unused snapshots can clutter the system and consume disk space. This functionality aids users in managing and decluttering their snapshot library, ensuring only relevant states are retained.

Explanation:

• --snapshot delete tag: Deletes the snapshot labeled with tag, freeing up resources and maintaining a clean working environment.
• --vm: Specifies the configuration file path.
• path/to/file.conf: The actual path to the configuration file.

Example Output: The command will confirm deletion of the specified snapshot, ensuring users are aware of the successful cleanup operation.

Conclusion:

Quickemu is a powerful tool that facilitates the efficient management of virtual machines with simplicity and speed. Through its diverse use cases, Quickemu allows users to effortlessly create, test, and manage virtual environments while maintaining system organization and functionality, making it an invaluable asset in any tech enthusiast’s toolkit.