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I have Windows Subsystem for Linux, but I don't know which version I have, and many things won't work in version 1. How do I check my version?

K7AAY
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    @Rinzwind You are welcome to join with me requesting such at https://github.com/microsoft/WSL/issues/4555 – K7AAY Sep 30 '19 at 18:07
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    From that thread, it looks like the following bash command works: `uname -r | grep Microsoft > /dev/null && echo "WSL1"`. -- It's a pretty adhoc way to detect it, but it will print "WSL1" if that's what you're running. – BrainSlugs83 Aug 12 '20 at 23:23
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    @BrainSlugs83 Extremely fragile but works for me! In WSL1, `uname -r` ends with `-Microsoft`, in WSL2, it ends `-microsoft-standard` ... lower case "m"! – Arthur Tacca Aug 14 '20 at 09:09
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    @Rinzwind Any questions regarding WSL, including how to install it, are on-topic, in my opinion. – Flimm Aug 24 '20 at 09:15
  • @Flimm not if the answer lies outside of wsl. As soon as someone mentions powershell it IS off topic We are NOT supposed to know anything that is a tool in Windows. – Rinzwind Aug 24 '20 at 09:25
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    @Rinzwind If the question is on-topic, then so are the answers to that question. If someone asks how to create a bootable Ubuntu USB stick on Windows, then that question is on-topic, and so are all the answers to it, even if the answers mention unetbootin.exe . Same thing with WSL. – Flimm Aug 25 '20 at 13:36
  • I would at least expect `wsl --version` to be available... – MC Emperor Oct 01 '20 at 07:51
  • Check the File Version in the Details tab of the Properties of C:\Windows\System32\Wsl.exe - if it is less than 10.0.19041.x then it is WSL1. – Oliver Slay Sep 05 '22 at 09:17

5 Answers5

173

  1. At a Windows 10 command prompt, run ver. Is the next-to-last numeric group version 18917 or higher? If so, it is possible you have WSL 2 but not yet verified. Go on to step A or B.
    If you do not see Windows version 18917 or higher, you have version 1.
    This illustrates the result when the OS is Build 16299:

    Version 16299

    A. Open Windows PowerShell or cmd and enter the command wsl -l -v. If version 2 is installed properly, you will see the version number. If you don't see a version number, or if you see an error message (Thank you, Cornea Valentin) you have version 1 (you may also see a version number '1' which could indicate that you're running v1 - see here). Uninstall it then reinstall it as per https://scotch.io/bar-talk/trying-the-new-wsl-2-its-fast-windows-subsystem-for-linux

    B. From the WSL shell prompt, run uname or uname -r. If the kernel version >= 4.19, it's WSL Version 2.

Why is this relevant?

WSL 1 was based on Microsoft's Linux-compatible kernel interface, a compatibility translation layer with no Linux kernel code.

WSL 2 was redesigned with a Linux kernel running in a lightweight VM environment, and innovators have found many more things they can do with WSL 2.

Windows 10 Version 2004 (build 19041.153 & later) enhances WSL2 further; see https://devblogs.microsoft.com/commandline/wsl2-will-be-generally-available-in-windows-10-version-2004/ and https://winaero.com/blog/wsl2-will-ship-with-windows-10-version-2004-with-kernel-updates-via-windows-update/ .

Community
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K7AAY
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    also if he get any errors after: wsl -l -v it's 100% wsl 1. – Cornea Valentin Oct 05 '19 at 15:04
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    I needed to use uname -r to see the kernel version, but the kernel version ended up being 4.4.0, which I'm pretty sure means WSL 1. – Keara Jun 12 '20 at 15:27
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    Use `uname -a` to print kernel version. – thisismydesign Jul 23 '20 at 11:35
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    For me, `wsl -l -v` prints the usage info (i.e. doesn't work), but `wsl -l --verbose` prints the verbose list as intended. `systeminfo.exe` gives me `OS Version: 10.0.19041 N/A Build 19041`. – drkvogel Aug 10 '20 at 14:35
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    According to [Microsoft](https://docs.microsoft.com/en-us/windows/wsl/install-win10) and a [Microsoft blogger](https://devblogs.microsoft.com/commandline/wsl-2-support-is-coming-to-windows-10-versions-1903-and-1909/#how-do-i-get-it), we can also get WSL2 on (1903 or 1909) build 18362.1049, due to a new backport. That helps those of us in companies that don't yet have build 18917, which is mentioned in the answer above. – Marcus Aug 28 '20 at 21:38
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    I'm seeing 4.4, is that greater or less than 4.19? – quant Sep 17 '20 at 22:48
  • In PS it is winver to see a popup with the Windows version – Timo Oct 24 '20 at 12:31
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    As of Dec 2020, typing `wsl -l -v` returns `VERSION 1` for me with `Ubuntu 20.04`. Nice fix for the newer Ubuntu v1. Cool! – Kyle Vassella Dec 15 '20 at 15:57
  • The mentioned link at https://scotch.io was perfect – Alireza Fattahi Dec 22 '20 at 06:41
  • What if I see `Invalid command line option: -l`? – Moberg Mar 01 '21 at 15:40
  • your answer contradicts itself - I am seeing a version number from the first test, suggesting it's version 2, but my kernel is lower than what you say is needed for version 2. – Rebroad May 01 '21 at 09:00
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  1. Open PowerShell
  2. Check the version with wsl -l -v
  3. If at version 1, then update the version with wsl --set-version Ubuntu-20.04 2

Note: Changing the version of a running OS will terminate it. The name of the OS need not be Ubuntu-20.04 for you. Please select the actual name listed in wsl -l -v

If you are not able to update to version 2, then you may not be on the WSL 2 Kernel. This can be downloaded from Microsoft.

Olivier Verdier
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Jack
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  • Note on point 3, running it will instantly kill currently running instances of the OS selected, eg all instances of Ubuntu-20.02 in this case. – zshift Aug 22 '20 at 21:40
  • Thanks for pointing that out, I added a note to point that out. – Jack Aug 23 '20 at 07:44
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    @Jack, Having only one version of ubuntu, 18.04, I noticed that "wsl --set-version Ubuntu 2" worked for me without specifying the version. I suspect that's always the case. – Angelo Aug 28 '20 at 01:05
  • This is the correct answer for me on Windows 10. – mLstudent33 Mar 29 '21 at 01:23
  • Simply run `wsl --status` as shown here: https://www.youtube.com/watch?v=bRW5r7TK6KM – Benny Code Jan 22 '22 at 23:40
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In the WSL version I was running, I just typed uname -r to which I got the result

5.4.72-microsoft-standard-WSL2

So, I can say that its WSL2, so you can try running uname -r and check.

Luce
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    That will work as long as you are running the stock kernel, but it could be named differently if you use a custom kernel. Also, for reference, WSL1 kernels are something like "4.4.0-22000-Microsoft" (without the "-standard-WSL2"). I seem to recall that 4.x releases on WSL2 were just "-microsoft-standard" (without the "-WSL2), but I could be wrong. – NotTheDr01ds Nov 27 '21 at 18:27
  • Ah I didn't know that, thanks for letting me know! – Luce Dec 08 '21 at 10:52
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    4.4.0-17763-Microsoft (Server 2019 WSL 1) – Jason Pyeron Dec 14 '22 at 21:27
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Programmatically:

# Multiline 
wsl.exe -l -v |
iconv -f utf16 |
egrep "\b${WSL_DISTRO_NAME}\s+Running" |
tr -d '\r' |
sed 's/.*\([[:digit:]]\)[[:space:]]*/\1/'

Will return 1 or 2.

Line-by-line, this:

  • Executes wsl.exe -l -v to return the full list of all distributions you might have installed

  • Runs it through iconv to fix its malformed UTF16 output. You don't normally see the problem unless you try to grep it (or pipe it to something like hexdump -C), but you have to clean it up before you can grep it.

  • Matches the current instance (via $WSL_DISTRO_NAME) line

  • Removes the DOS line ending

  • Finds the version number in the line and outputs it

Thanks to this Super User answer for the concept.

This will work as long as Interop is enabled for WSL.

If Interop isn't enabled, then a fallback method is to check /proc/cmdline:

  • /proc/cmdline on WSL1 is BOOT_IMAGE=/kernel init=/init
  • /proc/cmdline on WSL2 is initrd=\initrd.img panic=-1 pty.legacy_count=0 nr_cpus=16

So:

  • grep -q "^BOOT_IMAGE" /proc/cmdline returns success on WSL1 but error on WSL2
  • grep -q "^initrd" /proc/cmdline returns success on WSL2 but error on WSL1

This currently works (and has for the last year, at least), but could change in the future if either the WSL1 or WSL2 architecture changes in some way. However, I expect that the /proc/cmdline is likely always going to differ between WSL1 and WSL2 and can be programmatically parsed to determine the current version.

NotTheDr01ds
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-1

If you happen to be running Docker for Windows and you have WSL 1, then if you enter docker in the terminal for your WSL, you'll see the message The command 'docker' could not be found in this WSL 1 distro., which is a very clear confirmation.

Chris Halcrow
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