How can encoding of Write-Output be known and/or controlled?

[Liturgist]

Support Question

It appears that Write-Output in 5.1 output UTF-8, but 6.1 outputs something else.

$ od -Ax -tx1c  ps5.1.17763.315.txt
000000  ff  fe  61  00  0d  00  0a  00  62  00  0d  00  0a  00  63  00
       377 376   a  \0  \r  \0  \n  \0   b  \0  \r  \0  \n  \0   c  \0
000010  0d  00  0a  00
        \r  \0  \n  \0
000014

$ od -Ax -tx1c  ps6.1.1.txt
000000  61  0d  0a  62  0d  0a  63  0d  0a
         a  \r  \n   b  \r  \n   c  \r  \n
000009

These were created using Write-Output @('a','b','c')

Is 6.1 producing UTF-8 without BOM? 1252? 437? 8859-1? ???

[Jaykul]

Write-Output has no encoding. It outputs OBJECTS to the pipeline.

If you redirect text to an app you get the $OutputEncoding and if you redirect to file with > or >> or Out-File you get whatever you have in $PSDefaultParameterValues['Out-File:Encoding'] ...

I believe that the default for all of the above was "Unicode" (A.K.A. utf-16) up through PS 5.1 but in was been changed to utf-8 with no "Preamble" (A.K.A. BOM) -- I'm not totally sure because on my system I've set it differently.

You can control it by setting $PSDefaultParameterValues['*:Encoding']

In PowerShell 6 there's an option utf8NoBOM which is what it should be by default, but in PowerShell 5 there is only utf8 (with the pseduo BOM). You could use ascii but it's obviously, you know, ascii

[Liturgist]

Yes. 5.1

C:>$OutputEncoding

IsSingleByte      : True
BodyName          : us-ascii
EncodingName      : US-ASCII
HeaderName        : us-ascii
WebName           : us-ascii
WindowsCodePage   : 1252
IsBrowserDisplay  : False
IsBrowserSave     : False
IsMailNewsDisplay : True
IsMailNewsSave    : True
EncoderFallback   : System.Text.EncoderReplacementFallback
DecoderFallback   : System.Text.DecoderReplacementFallback
IsReadOnly        : True
CodePage          : 20127

6.1

PS C:\Users\pwatson> $OutputEncoding

Preamble          :
BodyName          : utf-8
EncodingName      : Unicode (UTF-8)
HeaderName        : utf-8
WebName           : utf-8
WindowsCodePage   : 1200
IsBrowserDisplay  : True
IsBrowserSave     : True
IsMailNewsDisplay : True
IsMailNewsSave    : True
IsSingleByte      : False
EncoderFallback   : System.Text.EncoderReplacementFallback
DecoderFallback   : System.Text.DecoderReplacementFallback
IsReadOnly        : True
CodePage          : 65001