How are PowerShell Modules (particularly PSReadline) loaded automatically in V5?

Question

I recently installed Windows 10, which includes V5 of PowerShell, or 5.1.14393.206 to be exact ($PSVersionTable.PSVersion).

On new computers I install PSReadline. However, Windows 10 comes with it already installed.

My question is, how is PSReadline loading automatically, when there is no profile to import it, (or call a command from it)?

As proof, I ran this code:

$PROFILE | Get-Member -MemberType NoteProperty | % {
    $path = $PROFILE.$($_.Name);
    $exists = Test-Path $path;
    [pscustomobject]@{ Path = $path; Exists = $exists }
}

To get this:

Path                                                                        Exists
----                                                                        ------
C:\Windows\System32\WindowsPowerShell\v1.0\profile.ps1                       False
C:\Windows\System32\WindowsPowerShell\v1.0\Microsoft.PowerShell_profile.ps1  False
C:\Users\tahir\Documents\WindowsPowerShell\profile.ps1                       False
C:\Users\tahir\Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1  False

I have gone through all of https://stackoverflow.com/a/23942543/288393:

• No call to Import-Module for PSReadline is made because there are no profiles to call it.
• No commands within PSReadline module are made because, as before, there are no profiles to call it.

Can someone explain this behavior?

Answer 1

There is special code in the console host to load PSReadline if the process is interactive. You can see the code here.