What are PowerShell profile locations on Linux?

On Windows, not counting ISE or x86, there are four (4) profile scripts.

AllUsersAllHosts @ C:\Program Files\PowerShell\6\profile.ps1
AllUsersCurrentHost @ C:\Program Files\PowerShell\6\Microsoft.PowerShell_profile.ps1
CurrentUserAllHosts @ C:\Users\lit\Documents\PowerShell\profile.ps1
CurrentUserCurrentHost @ C:\Users\lit\Documents\PowerShell\Microsoft.PowerShell_profile.ps1

On Linux with pwsh 6.2.0 I can find only two locations.

CurrentUserAllHosts @ ~/.config/powershell/Microsoft.PowerShell_profile.ps1
CurrentUserCurrentHost @ ~/.config/powershell/profile.ps1

Are there any "AllUsers" profile scripts on Linux? If so, where are they?

Solution

tl;dr (also applies to Windows):

The conceptual about_Profiles help topic describes PowerShell's profiles (initialization files).
The automatic $PROFILE variable contains a string that is the path of the initialization file for the current user and the current PowerShell host environment (typically, the terminal a.k.a console).
Additional profile files are defined - along the dimensions of (a) all-users vs. current-user and (b) all host environments vs. the current one - which are exposed via properties that the $PROFILE string variable is decorated with, which makes them nontrivial to discover - see below.
None of the profile files exist by default, and in some case even their parent directories may not; the bottom section of this answer shows programmatic on-demand creation and updating of the $PROFILE file.

Olaf provided the crucial pointer in comment:

$PROFILE | select *  # short for: $profile | Select-Object -Property *

shows all profile file locations, whether or not the individual profile files exist.

E.g., on my Ubuntu machine with PowerShell installed in /home/jdoe/.powershell, I get:

AllUsersAllHosts       : /home/jdoe/.powershell/profile.ps1
AllUsersCurrentHost    : /home/jdoe/.powershell/Microsoft.PowerShell_profile.ps1
CurrentUserAllHosts    : /home/jdoe/.config/powershell/profile.ps1
CurrentUserCurrentHost : /home/jdoe/.config/powershell/Microsoft.PowerShell_profile.ps1
Length                 : 62

^{Note the presence of the [string] type's native Length property, which you could omit if you used
$PROFILE | select *host* instead.}

That you can get the profile locations that way is not obvious, given that $PROFILE is a string variable (type [string]).
PowerShell decorates that [string] instance with NoteProperty members reflecting all profile locations, which is why select (Select-Object) is able to extract them.

Outputting just $PROFILE - i.e. the string value - yields /home/jdoe/.config/powershell/Microsoft.PowerShell_profile.ps1, i.e. the same path as its CurrentUserCurrentHost property, i.e. the path of the user-specific profile file specific to the current PowerShell host environment (typically, the terminal aka console).^[1]

You can verify the presence of these properties with reflection as follows, (which reveals their values too):

$PROFILE | Get-Member -Type NoteProperty

This means that you can also use regular property access and tab completion to retrieve individual profile locations; e.g.:

# Use tab-completion to find a specific profile location.
# Expands to .Length first, then cycles through the profile-location properties.
$profile.<tab>  

# Open the all-users, all-hosts profiles for editing.
# Note: Only works if the file already exists.
#       Also, you must typically run as admin to modify all-user profiles.
Invoke-Item $profile.AllUsersAllHosts

Convenience functions for getting profile locations and opening profiles for editing:

The code below defines:

Get-Profile enumerates profiles, showing their location and whether they exist on a given machine.
Edit-Profile opens profile(s) for editing (use -Force to create them on demand); note that modifying all-user profiles typically requires running as admin.

function Get-Profile {
  <#
  .SYNOPSIS
  Gets the location of PowerShell profile files and shows whether they exist.
  #>
  [CmdletBinding(PositionalBinding=$false)]
  param (
    [Parameter(Position=0)]
    [ValidateSet('AllUsersAllHosts', 'AllUsersCurrentHost', 'CurrentUserAllHosts', 'CurrentUserCurrentHost')]
    [string[]] $Scope
  )
  
  if (-not $Scope) {
    $Scope = 'AllUsersAllHosts', 'AllUsersCurrentHost', 'CurrentUserAllHosts', 'CurrentUserCurrentHost'
  }

  foreach ($thisScope in $Scope) {
    [pscustomobject] @{
      Scope = $thisScope
      FilePath = $PROFILE.$thisScope
      Exists = (Test-Path -PathType Leaf -LiteralPath $PROFILE.$thisScope)
    }
  }

}

function Edit-Profile {
  <#
  .SYNOPSIS
  Opens PowerShell profile files for editing. Add -Force to create them on demand.
  #>
  [CmdletBinding(PositionalBinding=$false, DefaultParameterSetName='Select')]
  param (
    [Parameter(Position=0, ValueFromPipelineByPropertyName, ParameterSetName='Select')]
    [ValidateSet('AllUsersAllHosts', 'AllUsersCurrentHost', 'CurrentUserAllHosts', 'CurrentUserCurrentHost')]
    [string[]] $Scope = 'CurrentUserCurrentHost'
    ,
    [Parameter(ParameterSetName='All')]
    [switch] $All
    ,
    [switch] $Force
  )
  begin {
    $scopes = New-Object Collections.Generic.List[string]
    if ($All) {
      $scopes = 'AllUsersAllHosts', 'AllUsersCurrentHost', 'CurrentUserAllHosts', 'CurrentUserCurrentHost'
    }
  }  
  process {
    if (-not $All) { $scopes.Add($Scope) }
  }

  end {
    $filePaths = foreach ($sc in $scopes) { $PROFILE.$sc }
    $extantFilePaths = foreach ($filePath in $filePaths) {
      if (-not (Test-Path -LiteralPath $filePath)) {
        if ($Force) {
          if ((New-Item -Force -Type Directory -Path (Split-Path -LiteralPath $filePath)) -and (New-Item -Force -Type File -Path $filePath)) {
              $filePath
          }
        } else {
          Write-Verbose "Skipping nonexistent profile: $filePath"
        }
      } else {
        $filePath
      }
    }
    if ($extantFilePaths.Count) {
      Write-Verbose "Opening for editing: $extantFilePaths"
      Invoke-Item -LiteralPath $extantFilePaths
    } else {
      Write-Warning "The implied or specified profile file(s) do not exist yet. To force their creation, pass -Force."
    }
  }

}

^{[1] PowerShell considers the current-user, current-host profile the profile of interest, which is why $PROFILE's string value contains that value. Note that in order to decorate a [string] instance with note properties, Add-Member alone is not enough; you must use the following idiom: $decoratedString = $string | Add-Member -PassThru propName propValue - see the Add-Member help topic.}