PowerShell WSL Interop

The Windows Subsystem for Linux (WSL) enables calling Linux commands directly within PowerShell via wsl.exe (e.g. wsl ls). While more convenient than a full context switch into WSL, it has the following limitations:

• Prefixing commands with wsl is tedious and unnatural
• Windows paths passed as arguments don't often resolve due to backslashes being interpreted as escape characters rather than directory separators
• Windows paths passed as arguments don't often resolve due to not being translated to the appropriate mount point within WSL
• Arguments with special characters (e.g. regular expressions) are often misinterpreted without unnatural embedded quotes or escape sequences
• Default parameters defined in WSL login profiles with aliases and environment variables aren’t honored
• Linux path completion is not supported
• Command completion is not supported
• Argument completion is not supported

The Import-WslCommand function addresses these issues in the following ways:

• By creating PowerShell function wrappers for commands, prefixing them with wsl is no longer necessary
• By identifying path arguments and converting them to WSL paths, path resolution is natural and intuitive as it translates seamlessly between Windows and WSL paths
• By formatting arguments with special characters, arguments like regular expressions can be provided naturally
• Default parameters are supported by $WslDefaultParameterValues similar to $PSDefaultParameterValues
• Environment variables are supported by $WslEnvironmentVariables
• Command completion is enabled by PowerShell's command completion
• Argument completion is enabled by registering an ArgumentCompleter that shims bash's programmable completion

The commands can receive both pipeline input as well as their corresponding arguments just as if they were native to Windows.

Additionally, they will honor any default parameters defined in a hash table called $WslDefaultParameterValues similar to $PSDefaultParameterValues. For example:

$WslDefaultParameterValues["grep"] = "-E"
$WslDefaultParameterValues["less"] = "-i"
$WslDefaultParameterValues["ls"] = "-AFh --group-directories-first"

If you use aliases or environment variables within your login profiles to set default parameters for commands, define a hash table called $WslDefaultParameterValues within your PowerShell profile and populate it as above for a similar experience.

Environment variables can also be set in a hash table called $WslEnvironmentVariables using the pattern $WslEnvironmentVariables["<NAME>"] = "<VALUE>".

The import of these functions replaces any PowerShell aliases that conflict with the commands.

Usage

• Install PowerShell Core
• Install the Windows Subsystem for Linux (WSL)
  • Ensure the bash-completion package is installed with sudo apt install bash-completion or equivalent command
• Install the WslInterop module with Install-Module WslInterop
• Import commands with Import-WslCommand
  • Import-WslCommand "apt", "awk", "emacs", "find", "grep", "head", "less", "ls", "man", "sed", "seq", "ssh", "sudo", "tail", "touch", "vim" for example
  • Add this to your profile for persistent access
• (Optionally) Define a hash table called $WslDefaultParameterValues and set default arguments for commands using the following patterns:
  • $WslDefaultParameterValues["<COMMAND>"] = "<ARGS>"
    • <ARGS> will be passed as default arguments to <COMMAND>
  • $WslDefaultParameterValues["<COMMAND>"] = { <SCRIPTBLOCK> }
    • <SCRIPTBLOCK> will be executed at runtime to determine the default arguments for <COMMAND>
  • $WslDefaultParameterValues["-d"] = "<DISTRIBUTION>"
    • The distribution WSL uses will be changed by setting wsl -d <DISTRIBUTION>
  • $WslDefaultParameterValues["-u"] = "<USERNAME>"
    • The username WSL uses will be changed by setting wsl -u <USERNAME>
  • $WslDefaultParameterValues["--shell-type"] = "<SHELLTYPE>"
    • The shell type WSL uses will be changed by setting wsl --shell-type <SHELLTYPE> where <SHELLTYPE> is either standard, login, or none
• (Optionally) Define a hash table called $WslEnvironmentVariables and set environment variables using the pattern $WslEnvironmentVariables["<NAME>"] = "<VALUE>" or use WSLENV

Known Issues

• Windows PowerShell is not supported. PowerShell Core is required.