{{ message }}
Repository navigation
Write-Host prints ANSI control characters when running script from stdin even if stdout is redirected #26631
Description
Prerequisites
- Write a descriptive title.
- Make sure you are able to repro it on the latest released version
- Search the existing issues.
- Refer to the FAQ.
- Refer to Differences between Windows PowerShell 5.1 and PowerShell.
Steps to reproduce
- Run a script from a Here-Document with output to a file (or a pipe etc), in Ubuntu Terminal:
$ pwsh -c - >out.txt <<!
> echo \$Env:PATH
> !
$ xxd out.txt
00000000: 1b5b 3f31 681b 5b3f 316c 2f6f 7074 2f6d .[?1h.[?1l/opt/m
00000010: 6963 726f 736f 6674 2f70 6f77 6572 7368 icrosoft/powersh
00000020: 656c 6c2f 373a 2f68 6f6d 652f 766d 7573 ell/7:/home/vmus
00000030: 6572 2f2e 7069 7869 2f62 696e 3a2f 686f er/.pixi/bin:/ho
<...>
00000150: 733a 2f73 6e61 702f 6269 6e3a 2f73 6e61 s:/snap/bin:/sna
00000160: 702f 6269 6e0a 1b5b 3f31 68 p/bin..[?1h- Notably, if you run the same script from a command line argument, the output works correctly:
$ pwsh -c 'echo $Env:PATH' >out.txt
vmuser@ubuntuvm:~/.pyenv$ xxd out.txt
00000000: 2f6f 7074 2f6d 6963 726f 736f 6674 2f70 /opt/microsoft/p
00000010: 6f77 6572 7368 656c 6c2f 373a 2f68 6f6d owershell/7:/hom
<..>
00000140: 6c2f 6761 6d65 733a 2f73 6e61 702f 6269 l/games:/snap/bi
00000150: 6e3a 2f73 6e61 702f 6269 6e0a n:/snap/bin.Expected behavior
With $PsStyle.OutputProcessing="Host", ANSI escape sequences should be written to a stream only if it points to a terminal (isatty returns 1).
This is the default behavior of standard UNIX console programs that can print ANSI escape sequences.
Actual behavior
(see above in reproduction steps)
- Whether stderr is also redirected does not affect the behavior
Error details
N/A
Environment data
Name Value
---- -----
PSVersion 7.5.4
PSEdition Core
GitCommitId 7.5.4
OS Ubuntu 24.04.3 LTS
Platform Unix
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0Visuals
No response
Activity
mklement0 commentedon Dec 20, 2025
Please see:
$PSStyle.OutputRendering = 'Host', outputs ANSI/VT escape sequences unconditionally #20170Conceptually related:
pwsh -Command -andpwsh -File -unexpectedly exhibit pseudo-interactive behavior, lack support for argument passing #3223SeeminglyScience commentedon Oct 5, 2026
The Engine WG discussed this, we agree that the host should not be emitting these VT sequences when processing stdin as commands.
For reference:
Here's where they are defined in the code.
Here's the PR where it was added.
candygoogy commentedon Oct 11, 2026
I'm working on this: not emitting those VT sequences when commands come from stdin, while keeping the interactive behaviour from #14943. @PowerShell/powershell could you assign it to me?