document XDG env variables for Unix

[SteveL-MSFT]

PowerShell Core 6 will use these env vars if defined on Unix:

XDG_CONFIG_HOME, XDG_CACHE_HOME, and XDG_DATA_HOME

Issue Details

Version(s) of document impacted

• Impacts 5.1 document
• Impacts 5.0 document
• Impacts 4.0 document
• Impacts 3.0 document

Reason(s) for not selecting all version of documents

• The documented feature was introduced in selected version of PowerShell
• This issue only shows up in selected version of the document

[sdwheeler]

@SteveL-MSFT How will these environment variables be used? What document should this go in?

[SteveL-MSFT]

Typically, an end user does not need to do anything with these environment variables and they only apply to non-Windows.

XDG_CONFIG_HOME defaults to ~/.config/powershell
XDG_DATA_HOME defaults to ~/.local/share/powershell
XDG_CACHE_HOME defaults to ~/.cache/powershell

XDG_CONFIG_HOME is path used to find the powershell profile.ps1 script if it exists
XDG_DATA_HOME is used for the user module path: XDG_DATA_HOME/modules
XDG_CACHE_HOME is used for cache files produced by PowerShell (like the module discovery cache)

The only time a user needs to define these if if they are using powershell from an account that doesn't have a home directory (like a service account).

[sdwheeler]

This is covered in https://docs.microsoft.com/en-us/powershell/scripting/whats-new/what-s-new-in-powershell-core-60