wslconfig.exe: Windows Subsystem for Linux Configuration Tool

wslconfig.exe is a command-line utility included with Windows that allows you to manage your Windows Subsystem for Linux (WSL) installations. It's used to list available distributions, set defaults, and unregister or terminate running distributions. It is not a virus and is a legitimate component of Windows. It cannot "become" a virus, although a malicious file could be named wslconfig.exe and placed in a different directory to try to trick users. The legitimate wslconfig.exe is always located in the %SystemRoot%\System32 directory (typically C:\Windows\System32).

Purpose and Functionality

wslconfig.exe provides a way to interact with WSL distributions without needing to launch a WSL instance directly. Its primary functions are:

• Listing Distributions: Displaying the installed WSL distributions and their current status (running, stopped, etc.).
• Setting Default Distribution: Specifying which Linux distribution should be launched when you use the wsl command without any distribution-specific arguments.
• Unregistering Distributions: Removing a WSL distribution from your system. This effectively uninstalls the distribution and deletes its associated filesystem.
• Terminating Distributions: Stopping a currently running WSL distribution.
• Import/Export Distributions (WSL 2): Although not the primary function, wsl.exe itself (not wslconfig.exe) is best for Import/Export. wslconfig.exe's role is in managing existing installations.

Usage

wslconfig.exe is used from the Command Prompt or PowerShell. You do not double-click it to run it. It is used exclusively with command-line arguments. Here are the common commands:

• /l, /list [Options]: Lists installed distributions.

  • /all: Lists all distributions, including those that are currently being installed or uninstalled.
  • /running: Lists only the distributions that are currently running.
  • (No option): Lists the registered distributions.
  • /online or /o: Lists available distributions for online installation (using wsl --install -d ).

  powershell wslconfig /list /all # Lists all distributions, even those installing/uninstalling. wslconfig /l /running # Shows only currently running distributions. wslconfig /l /online # Shows available distributions to install online. * /s, /setdefault <DistributionName>: Sets the specified distribution as the default.

  powershell wslconfig /setdefault Ubuntu-20.04 # Makes Ubuntu-20.04 the default. * /t, /terminate <DistributionName>: Terminates (stops) the specified running distribution.

  powershell wslconfig /terminate Ubuntu-22.04 # Stops Ubuntu-22.04. * /u, /unregister <DistributionName>: Unregisters (uninstalls) the specified distribution. Warning: This deletes the distribution's filesystem!

  powershell wslconfig /unregister Debian # Uninstalls and removes the Debian distribution.

Important Considerations:

• Distribution Names: You can usually find the exact distribution name by running wslconfig /list. The name is case-sensitive.
• WSL vs. WSL 2: While wslconfig.exe works with both WSL 1 and WSL 2 distributions, some features (like importing/exporting) are primarily handled by wsl.exe and are more relevant to WSL 2.
• wsl.exe vs. wslconfig.exe: wsl.exe is the primary command for interacting with WSL. It's used to launch distributions, run commands within them, and manage more advanced settings. wslconfig.exe is more focused on managing the distributions themselves. Think of wsl.exe as the main interface, and wslconfig.exe as a supplementary administrative tool. For instance, to export or import a distribution you will use wsl.exe --export <Distro> <FileName> and wsl.exe --import <Distro> <InstallLocation> <FileName>.

Is it a Virus?

No, wslconfig.exe is not a virus. It's a legitimate part of Windows. However, as with any executable file, it's theoretically possible for malware to masquerade as wslconfig.exe. To verify that you're dealing with the genuine wslconfig.exe, check its location:

1. Open Task Manager: (Ctrl+Shift+Esc).
2. Find a WSL Process (if one is running): If you have a WSL distribution running (e.g., Ubuntu), you might see a process related to it. However, wslconfig.exe itself won't usually be running unless you're actively using it from the command line. You would be looking for the wsl.exe in this case, if a distro is launched.
3. Right-click on any WSL process (or wsl.exe or cmd.exe if you just executed wslconfig) and choose "Open file location." This should take you to C:\Windows\System32. If the file is located anywhere else, it's suspicious. Also, for wslconfig.exe, the best way to verify is to not have any WSL distros running. Then, run where wslconfig from cmd.exe.
4. Verify the Digital Signature: Right-click the wslconfig.exe file in C:\Windows\System32, select "Properties," and go to the "Digital Signatures" tab. It should be signed by "Microsoft Windows."

If you're still concerned, run a scan with your antivirus software.

Troubleshooting

• wslconfig command not found: If you get an error saying the command is not found, make sure that:

  • WSL is enabled. You can enable it through "Turn Windows features on or off" (search for it in the Start menu). You need to enable both "Windows Subsystem for Linux" and (for WSL 2) "Virtual Machine Platform."
  • Your PATH environment variable is correctly configured. It should include C:\Windows\System32. This is usually set up correctly by default.

• Errors listing distributions: If wslconfig /list produces errors, it could indicate a problem with your WSL installation. Try restarting your computer, and if that doesn't work, consider repairing or reinstalling WSL.

• Distro name not recognized: Be careful to use the exact, case sensitive distro name. wslconfig /list will show the proper names.

In summary, wslconfig.exe is a safe and essential utility for managing your WSL installations. Understanding its purpose and usage is crucial for effectively using the Windows Subsystem for Linux.