Select-String highlighting / emphasis only works on first Select-String

[LeeHolmes]

Prerequisites

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• Make sure you are able to repro it on the latest released version
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• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

The highlighting / emphasis from Select-String is only done for the first instance of Select-String in the pipeline. It should be the last since it is a highlighting technique.

Expected behavior

PowerShell 7.3.6

[C:\Users\lee]
PS:1 > "Hello World" | Select-String Hello

>>Hello<< World


[C:\Users\lee]
PS:2 > "Hello World" | Select-String World

Hello >>World<<


[C:\Users\lee]
PS:3 > "Hello World" | Select-String Hello | Select-String World

Hello >>World<<


[C:\Users\lee]
PS:4 > "Hello World" | Select-String Hello -NoEmphasis | Select-String World

Hello >>World<<

Actual behavior

PowerShell 7.3.6

[C:\Users\lee]
PS:1 > "Hello World" | Select-String Hello

>>Hello<< World


[C:\Users\lee]
PS:2 > "Hello World" | Select-String World

Hello >>World<<


[C:\Users\lee]
PS:3 > "Hello World" | Select-String Hello | Select-String World

>>Hello<< World


[C:\Users\lee]
PS:4 > "Hello World" | Select-String Hello -NoEmphasis | Select-String World

Hello World
(no highlighting / emphasis at all)

Error details

No response

Environment data

Name                           Value
----                           -----
PSVersion                      7.3.6
PSEdition                      Core
GitCommitId                    7.3.6
OS                             Microsoft Windows 10.0.22000
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

[LeeHolmes]

Context - I was trying to create a screen shot to point out some SQL injection issues. These are only in lines with "SELECT" or "UPDATE" in them, but what I wanted to point out was the actual variable that was injectable.

I was able to do this only by reversing the order of Select-String statements, which was inefficient and nobody would be able to figure out.

[237dmitry]

"Hello World" | Select-String Hello | Select-String World

You are trying to get matches from non-string object. Select-String Hello returns Microsoft.PowerShell.Commands.MatchInfo

Use regex to get all matches selected:

"Hello World" | sls 'Hello|World' -all
"Hello World" | sls '\w+' -all

[LeeHolmes]

Select-String understands how to handle MatchInfo objects from earlier in the pipeline:

PowerShell/src/Microsoft.PowerShell.Commands.Utility/commands/utility/MatchString.cs

Line 1538 in 0502da7

matchInfo = _inputObject.BaseObject as MatchInfo;

It's just that highlighting doesn't do what user expectations would be (to highlight the items from the last in the pipeline).

[237dmitry]

Select-String understands how to handle MatchInfo objects from earlier in the pipeline

I am not sure, pipelines return the first matchinfo:

PS > ("Hello World" | sls Hello | sls World).Pattern
Hello

[mklement0]

@237dmitry, your example (a) proves that MatchInfo objects are passed through and (b) reveals a different bug (also implied by the PS:3 > command output in the "Visuals" section in the initial post), which I encourage you to file as such.

As an aside: chaining Select-String calls is also problematic in other respects:

• See Revisit the behavior of chaining Select-String calls #14850

[237dmitry]

proves that MatchInfo objects are passed through

The second Select-String just does not find matches. Because its input is not a string. I think so.

[mklement0]

@237dmitry, clearly it does find matches (just execute "Hello World" | sls Hello | sls World on its own).

• See Chaining Select-String calls mistakenly passes the first call's .Pattern property value through #20063

[jhoneill]

Select-String understands how to handle MatchInfo objects from earlier in the pipeline:

PowerShell/src/Microsoft.PowerShell.Commands.Utility/commands/utility/MatchString.cs

Line 1538 in 0502da7

matchInfo = _inputObject.BaseObject as MatchInfo;

It's just that highlighting doesn't do what user expectations would be (to highlight the items from the last in the pipeline).

It appears that if the input object is a match info object, the behaviour is something like where {$_.tostring() -match $pattern} it doesn't create a new matchinfo with new highlighting etc. I can't tell if there is a reason for doing that because we might expect it to turn the matchinfo into a string and create a new matchinfo object. It looks like someone deliberately stopped that happening but no reason for doing that is suggesting itself to me.

[mklement0]

The behavior is like Where-Object { $_.Line -match $Pattern }, as described in #14850 ($_.ToString() would include -Context lines, but with for-display formatting).

[jhoneill]

This and #20063 do appear to be completely covered in #14850 which is languishing in the "still needs triage" pile.
I suspect that the answer to #14850 will be "this is by design". There's a case to be made that the design was to support to something that in practice people don't generally do and they expect something different, so the design should be revised. But "breaking change" etc.