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Windows subsystem for Linux 2 (WSL2)

Set up Windows subsystem for Linux 2 (WSL2) for Linux development experience in Windows 10 and 11.

Instal WSL2

Open powershell with administrator privilege, run the following command in the host.

wsl --install --no-distribution

or install the components manually

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart
dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

After reboot, install the Linux distribution

wsl --update
wsl --set-default-version 2
wsl --install -d Ubuntu  # Or another Linux distribution

WSL2 post-install (optional) setup

Backup/move the virtual disk

If you want to move the WSL virtual disk file to another disk (in this example, D:\), run the following commands in Windows12:

wsl --export Ubuntu .\Ubuntu\ext4.tar
wsl --unregister Ubuntu
wsl --import Ubuntu D:\Ubuntu\ .\Ubuntu\ext4.tar

Default login user

Edit /etc/wsl.conf in the WSL. You may need to set the default user if you have moved the virtual disk file of the WSL distribution.

/etc/wsl.conf
[user]
default=username

Host settings

Edit .wslconfig 3 in your Windows home directory (%USERPROFILE%).

For example,

.wslconfig
[wsl2]
memory=20GB              # How much memory to assign to the WSL2 VM.
swap=8GB                 # How much swap space to add to the WSL2 VM. 0 for no swap file.
swapfile=C:\\temp\\wsl-swap.vhdx # Sets swap file path location, default is %USERPROFILE%\AppData\Local\Temp\swap.vhdx. Useful if your C drive has limited disk space.

Auto reclaim RAM and disk space

Edit .wslconfig 3 in your Windows home directory (%USERPROFILE%). 4

.wslconfig
[experimental]
autoMemoryReclaim=gradual    # Reclaim RAM usage
sparseVhd=true               # Reclaim virtual disk (vhd) usage

Maintenance

Update kernel

To (manually) update the WSL kernel, run the following commands with administrator privileges:

wsl --shutdown
wsl --update

Reclaim virtual disk space

Optimize-VHD

Note

Optimize-VHD is not available in Windows Home edition.

To reclaim disk space from virtual hard disks (VHDs), run the following commands with administrator privileges 5:

wsl --shutdown
Optimize-VHD -Path %path-to.vhdx% -Mode Full
Export and re-import

Alternatively, export the VHD as a tar file and reimport it again.

Caveats about WSL2

Poor filesystem performance across OSes

Cross-OS file access (e.g., accessing /mnt/c in WSL) is at least one order of magnitude (10x) slower than accessing natively (/home/user/).6

  1. https://learn.microsoft.com/zh-tw/windows/wsl/basic-commands#import-and-export-a-distribution ↩↩↩

  2. https://blog.iany.me/2020/06/move-wsl-to-another-drive/ ↩↩↩

  3. https://learn.microsoft.com/zh-tw/windows/wsl/wsl-config ↩↩↩↩↩↩

  4. https://devblogs.microsoft.com/commandline/windows-subsystem-for-linux-september-2023-update/ ↩↩↩

  5. https://blog.miniasp.com/post/2023/05/14/Shrink-your-WSL2-Virtual-Disks-and-Docker-Images-and-Reclaim-Disk-Space ↩↩↩

  6. https://neilbryan.ca/posts/win10-wsl2-performance/ ↩↩↩

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Check battery status

Open Windows Powershell with Administrator rights and run:

powercfg /batteryreport /output "C:\battery-report.html"

See the report at C:\battery-report.html.

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Install fonts in Linux

Copy the fonts files to ~/.local/share/fonts/. Then, run fc-cache to rebuild fonts cache.

fc-cache -fv
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Environment variables

Linux environment variables

Arch Wiki: environment variables

System-wide

  • /etc/profile is sourced by all POSIX-compatible shells upon login.
  • Files inside the /etc/profile.d/ directory will also be read.

Bash

  • ~/.profile or ~/.bash_profile for login bash instances.
  • ~/.bashrc for every interactive bash instance.

Zsh

  • ~/.zshenv for environment variables in all zsh instances.
  • ~/.zprofile for every login zsh instance.
  • ~/.zshrc for every interactive zsh instance.

Note

zsh does not source ~/.profile by default because of the difference between bash and zsh syntaxes. You can add this line to ~/.zprofile or ~/.zshenv to make zsh shells read `~/.profile correctly.

~/.zshenv
skip_global_compinit=1
test -r ${HOME}/.profile && emulate sh -c 'source ${HOME}/.profile'

X Window

  • ~/.xinitrc is sourced by startx.
  • ~/.xprofile is sourced by display managers (e.g., GDM, SDDM)

Systemd and Wayland

  • ~/.config/environment.d/*.conf: sourced by systemd. Also, they are used in Wayland sessions where xinitrc and xprofile files are not available.

Windows environment variables

Environment variables in Powershell

Session variables

Variables created by set are bound to the current session and not persistent.

$Env:FOO = "example"
$Env:FOO

Persistent variables

  • GUI: Windows Settings -> Advanced system settings -> Set Environment Variables.
  • Powershell: [Environment]::SetEnvironmentVariable('KEY', 'VAL', 'Machine')
  • Cmd: SETX KEY VAL