Add -IncludeTimeStamp and -TimeStampFormat parameters to Start-Transcript by soroshsabz · Pull Request #28230 · PowerShell/PowerShell

soroshsabz · 2026-10-19T05:42:41Z

PR Summary

Add opt-in -IncludeTimeStamp and -TimeStampFormat parameters to Start-Transcript that prefix each recorded line of command input and output with a timestamp, so long-running or headless scripts can be reviewed chronologically without cross-referencing external logs.

Start-Transcript ./log.txt -IncludeTimeStamp
Write-Host "This is a test"
Start-Sleep -Seconds 180
Write-Host "The end"
Stop-Transcript

Get-Content log.txt
...
2026-10-19 11:04:52 This is a test
2026-10-19 11:07:52 The end

The timestamp format defaults to yyyy-MM-dd HH:mm:ss (invariant culture, local time) and can be customized with any .NET date and time format string — both standard (e.g. o, s, R) and custom:

Start-Transcript ./log.txt -TimeStampFormat "ddd HH:mm:ss.fff"
Write-Host "This is a test"
Stop-Transcript

Get-Content log.txt
...
Wed 19:08:44.751 This is a test

Specifying -TimeStampFormat implies -IncludeTimeStamp. Invalid format strings (including formats that would render multi-line output and corrupt the transcript) fail fast with a terminating InvalidTimeStampFormat error before any file is created.

PR Context

This PR fixes #24135

Additional design notes:

The timestamp is applied when output is queued to the transcript buffer rather than when it is flushed to disk, so it reflects the time the output was actually produced.
Multi-line entries (e.g. error records, native command output) have each non-empty line prefixed, as are echoed command lines (PS> ... / >> ...).
The transcript header/footer and -IncludeInvocationHeader banners are left unchanged since they already embed timestamps.
The feature is opt-in; without the switches, transcript output is byte-identical to before. This keeps existing ingestion mechanisms (e.g. JEA transcript collectors) unaffected, as discussed in the issue.
Known limitation: timestamps reflect the time a line was recorded to the transcript. Standalone native command output on Windows is captured from the console screen buffer once the process exits (the console buffer does not track per-line write times), so all lines of such a command receive the command's completion time. Piping native command output into a PowerShell command (e.g. native.exe | Out-Host) streams it through transcription line by line, so each line gets an accurate timestamp; redirecting native output directly to a file (e.g. native.exe > out.txt) bypasses transcription entirely.

PR Checklist

Add an opt-in IncludeTimeStamp switch to Start-Transcript that prefixes each transcribed line of command input and output with the time it was recorded, formatted as 'yyyy-MM-dd HH:mm:ss' using the invariant culture and local time. The timestamp is applied when output is queued to the transcript (in TranscriptionCommand/TranscribeResult via the new TranscriptionOption.AddOutput helper), so it reflects the time the output was produced rather than the time it was flushed to disk. Multi-line entries have each non-empty line prefixed. Transcript header/footer and IncludeInvocationHeader banners are left unchanged since they already contain timestamps. Without the switch, transcript output is byte-identical to before. Resolves PowerShell#24135

azure-pipelines · 2026-10-19T05:42:53Z

Azure Pipelines: There may be pipelines that require an authorized user to comment /azp run to run.

Copilot

🟡 Changes recommended

Screen-scraped Windows native output receives completion-time timestamps rather than individual line-production times.

1 open issue

Native output lines all receive the process completion timestamp · New

What changed in this PR

Adds opt-in transcript timestamps to support chronological log review, addressing #24135.

Changes:

Exposes Start-Transcript -IncludeTimeStamp.
Prefixes non-empty command and output lines when queued, leaving headers unchanged.
Adds tests for timestamped output and default behavior.

File	Description
test/powershell/Modules/Microsoft.Powershell.Host/Start-Transcript.Tests.ps1	Tests timestamp prefixes, multiline output, and default behavior.
src/System.Management.Automation/engine/hostifaces/MshHostUserInterface.cs	Stores the option and timestamps queued transcript content.
src/Microsoft.PowerShell.ConsoleHost/host/msh/StartTranscriptCmdlet.cs	Exposes and forwards the new switch.

_{Review effort: Balanced}

Standalone native command output on Windows is screen-scraped from the console buffer only after the process exits, so with -IncludeTimeStamp every line of that block receives the completion time of the command. The console buffer does not record per-line write times, so per-line production times cannot be recovered for this path without redirecting the native output, which would change how the command renders to the console. Piped or redirected native output already streams through transcription line by line and gets accurate per-line timestamps. Document this in the Start-Transcript parameter help and at the screen-scrape transcription site, and add a regression test for timestamped native command output (piped, so it does not depend on a physical console being available in the test environment).

Copilot

🟡 Changes recommended

The redirection guidance incorrectly promises transcript capture for output redirected to a file.

1 open issue

Correct redirection guidance to preserve timestamped transcript output · New

1 resolved since last review

Native output lines all receive the process completion timestamp

_{Review effort: Balanced}

Redirecting native command output directly to a file (for example 'native.exe > out.txt') transfers the bytes straight to the file and bypasses transcription entirely, so it must not be suggested as a way to capture per-line output. Only piping the native output into a PowerShell command (for example 'native.exe | Out-Host') streams it through the pipeline, where each line is recorded and timestamped as it is produced. Fix the guidance in the IncludeTimeStamp parameter help, the screen-scrape comment in NativeCommandProcessor, and the PR description accordingly.

Copilot

🟢 Approval recommended

No unresolved blocking issues remain; timestamping is opt-in, with focused tests and documented limitations.

No open issues 🎉

1 resolved since last review

Correct redirection guidance to preserve timestamped transcript output

_{Review effort: Balanced}

Add a TimeStampFormat parameter that accepts a .NET custom date and time format string (for example 'HH:mm:ss' or 'ddd yyyy-MM-dd HH:mm:ss.fff') for the timestamp prefix applied by -IncludeTimeStamp. The default format remains 'yyyy-MM-dd HH:mm:ss', rendered with the invariant culture. Specifying -TimeStampFormat implies -IncludeTimeStamp, so the switch does not need to be supplied as well. The format is validated up front by rendering a sample timestamp, so invalid format strings (or formats that would render multi-line output and corrupt the transcript) fail fast with a terminating InvalidTimeStampFormat error before any file is created.

DateTime.ToString already accepts both standard format strings (such as 'o', 's' and 'R') and custom format strings, and the sample-render validation accepts both, so standard format strings already work with -TimeStampFormat. Update the parameter documentation and the InvalidTimeStampFormat error message to reference both the standard and custom format string documentation, and add tests for a standard format string ('s') and for an unknown single-character specifier ('q'), which is rejected.

microsoft-github-policy-service · 2026-10-29T16:59:03Z

This pull request has been automatically marked as Review Needed because it has been there has not been any activity for 7 days.
Maintainer, please provide feedback and/or mark it as Waiting on Author

soroshsabz · 2026-11-08T20:05:51Z

/azp run

azure-pipelines · 2026-11-08T20:05:58Z

Commenter does not have sufficient privileges for PR 28230 in repo PowerShell/PowerShell

soroshsabz · 2026-11-08T20:14:13Z

Dongbo Wang (@daxian-dbw) could you please review this PR?

soroshsabz requested a review from a team as a code owner October 19, 2026 05:42

Copilot AI balanced review requested due to automatic review settings October 19, 2026 05:42

Copilot started reviewing on behalf of soroshsabz October 19, 2026 05:44

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Comment thread src/System.Management.Automation/engine/hostifaces/MshHostUserInterface.cs Resolved

soroshsabz requested a balanced review from Copilot October 20, 2026 16:25

Merge branch 'master' into feature/add-timestamp-to-transcript

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Copilot started reviewing on behalf of soroshsabz October 20, 2026 16:27

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Comment thread src/Microsoft.PowerShell.ConsoleHost/host/msh/StartTranscriptCmdlet.cs Resolved

soroshsabz added 2 commits October 21, 2026 13:13

Merge branch 'master' into feature/add-timestamp-to-transcript

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soroshsabz requested a balanced review from Copilot October 21, 2026 09:46

Copilot started reviewing on behalf of soroshsabz October 21, 2026 09:48

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soroshsabz added 2 commits October 21, 2026 19:10

soroshsabz mentioned this pull request Oct 21, 2026

Update Start-Transcript docs for new timestamp parameters MicrosoftDocs/PowerShell-Docs#13339

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soroshsabz changed the title ~~Start-Transcript: Add -IncludeTimeStamp parameter~~ Add -IncludeTimeStamp and -TimeStampFormat parameters to Start-Transcript Oct 21, 2026

Merge branch 'master' into feature/add-timestamp-to-transcript

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microsoft-github-policy-service Bot added the Review - Needed The PR is being reviewed label Oct 29, 2026

soroshsabz added 2 commits October 29, 2026 18:14

Merge branch 'master' into feature/add-timestamp-to-transcript

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Merge branch 'master' into feature/add-timestamp-to-transcript

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Add -IncludeTimeStamp and -TimeStampFormat parameters to Start-Transcript - #28230

Add -IncludeTimeStamp and -TimeStampFormat parameters to Start-Transcript#28230
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