PowerShell output with color redirected to file

dir color output to file

If I run the following command on Ubuntu:

dharmatech@dharmatech-01:/tmp$ pwsh -Command 'dir' > out.txt

and then cat the output:

dharmatech@dharmatech-01:/tmp$ cat out.txt

the colors are rendered:

The colors are represented in out.txt as escape codes:

Write-Host colors

Here I'm using Write-Host to display text in red:

However, if I redirect output to a file, we can see that this time the colors are not represented in the resulting file:

Question

Is there a way to get the colors in the file in the Write-Host case as they are with the dir command?

Starting in Windows PowerShell 5.0, Write-Host writes InformationRecord objects to the information stream. This will show if you redirect the information stream to the success stream using 6>&1:

$InformationRecord = Write-Host abc -ForegroundColor Red 6>&1
$InformationRecord | Get-Member

   TypeName: System.Management.Automation.InformationRecord

Name            MemberType Definition
----            ---------- ----------
Equals          Method     bool Equals(System.Object obj)
GetHashCode     Method     int GetHashCode()
GetType         Method     type GetType()
ToString        Method     string ToString()
Computer        Property   string Computer {get;set;}
ManagedThreadId Property   uint ManagedThreadId {get;set;}
MessageData     Property   System.Object MessageData {get;}
NativeThreadId  Property   uint NativeThreadId {get;set;}
ProcessId       Property   uint ProcessId {get;set;}
Source          Property   string Source {get;set;}
Tags            Property   System.Collections.Generic.List[string] Tags {get;}
TimeGenerated   Property   datetime TimeGenerated {get;set;}
User            Property   string User {get;set;}

This object holds the color information in the MessageData property and doesn't include any ANSI control codes by itself:

$InformationRecord.MessageData | Get-Member

   TypeName: System.Management.Automation.HostInformationMessage

Name            MemberType Definition
----            ---------- ----------
Equals          Method     bool Equals(System.Object obj)
GetHashCode     Method     int GetHashCode()
GetType         Method     type GetType()
ToString        Method     string ToString()
BackgroundColor Property   System.Nullable[System.ConsoleColor] BackgroundColor {get;set;}
ForegroundColor Property   System.Nullable[System.ConsoleColor] ForegroundColor {get;set;}
Message         Property   string Message {get;set;}
NoNewLine       Property   System.Nullable[bool] NoNewLine {get;set;}

In other words, I don't think that there is any way to preserve the ANSI control code fromWrite-Host. See also: Is there a way to preserve ANSI control codes in PowerShell command output?

You might consider to write your own Write-Ansi proxy command based on Write-Host but there is a general disadvantage with using the Write-Host command as you can only use a single color for the whole output which requires to make use of the -NoNewLne switch and take that in consideration for any proxy command.

Alternatives

Instead of a using a limited (not redirectable) command like:

Write-Host 'This whole line is red.' -ForegroundColor Red

You might consider using the $PSStyle object:

 "This is $($PSStyle.Foreground.Red)red$($PSStyle.Reset) text" #  > .\out.txt

Or, using MarkDown:

'Make this *blue* text' > .\out.txt
(Get-Content .\out.txt | ConvertFrom-MarkDown -AsVT100EncodedString).VT100EncodedString

Or even:

Set-MarkdownOption -ItalicsForegroundColor '[91m'
('Make this *red* text' | ConvertFrom-MarkDown -AsVT100EncodedString).VT100EncodedString > .\out.txt
Get-Content .\out.txt

Here's one approach using the script command from bsdutils:

This is based on this answer:

> https://stackoverflow.com/a/27399198/268581

Use case

As an aside, by combining this approach with terminal-to-html:

> https://github.com/buildkite/terminal-to-html

I'm able to render arbitrary colored PowerShell output as HTML.

Here's a screenshot which renders output from this PowerShell script as HTML:

> https://github.com/dharmatech/net-liquidity.ps1

This should be possible since Powershell 7.2, as it has support for ANSI colors. Credit for this goes to an earlier answer.

As for an example (Powershell 7.3.3. / MacOS, YMMV):

$PsStyle.OutputRending = "Ansi"
$s = Get-ChildItem | Select -First 3 | Out-String
Set-Content -path foo.txt $s
Get-Content ./foo.txt # prints out colored output

Examining the file with, say, vi displays the Ansi color codes:

...
^[[32;1mUnixMode   User     Group     LastWriteTime    Size   Name^[[0m
^[[32;1m--------   -        -----     -------------    ----   ----^[[0m
...