PowerShell.MCP v1.3.8 - Visual -WhatIf Preview for Remove-LinesFromFile & Safety Improvements

[yotsuda]

Visual -WhatIf Preview for Remove-LinesFromFile & Safety Improvements

This release adds visual diff preview to Remove-LinesFromFile, safer deletion handling for Update-LinesInFile, newline validation across all pattern-matching cmdlets, and performance improvements to Update-MatchInFile.

✨ What's New

🔍 Visual -WhatIf Preview for Remove-LinesFromFile

Remove-LinesFromFile -WhatIf now displays a detailed preview showing exactly which lines will be deleted:

• Red highlighting for lines being removed
• Yellow background for matched pattern/text within deleted lines
• Surrounding context lines for clarity
• No file modification until you confirm

# Preview which lines will be deleted
Remove-LinesFromFile log.txt -Contains "ERROR" -WhatIf

# Output shows:
#   1- Previous line
#   2: Error message here     ← Red with "ERROR" highlighted in yellow
#   3- Next line

⚡ Performance: Update-MatchInFile Single-Pass Processing

Update-MatchInFile has been refactored from 2-pass to 1-pass processing, reading the file only once instead of twice. This improves performance especially for large files.

🛡️ Safer Deletion Handling for Update-LinesInFile

Update-LinesInFile now requires -Content parameter when -LineRange is specified:

# Explicit deletion (works as before)
Update-LinesInFile file.txt -LineRange 5,10 -Content @()

# Omitting -Content now throws an error (previously would silently delete)
Update-LinesInFile file.txt -LineRange 5,10  # Error!

This prevents accidental line deletion when -Content is forgotten.

🚫 Newline Validation for Pattern Parameters

All cmdlets with -Pattern or -Contains parameters now reject newline characters:

# These now throw errors immediately (instead of silently failing to match)
Show-TextFile file.txt -Pattern "line1`nline2"      # Error!
Update-MatchInFile file.txt -Contains "a`nb" -Replacement "x"  # Error!
Remove-LinesFromFile file.txt -Pattern "multi`nline"  # Error!

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📊 What's Changed Since v1.3.7

New Features

Visual -WhatIf Preview:

• Remove-LinesFromFile -WhatIf shows lines to be deleted in red
• Pattern/Contains matches highlighted with yellow background
• Context lines displayed for clarity

Pipeline Input Support:

• Add-LinesToFile -Content now accepts pipeline input
• Update-LinesInFile -Content now accepts pipeline input

Improvements

Performance:

• Update-MatchInFile refactored from 2-pass to 1-pass processing (reads file once instead of twice)

Display:

• Update-MatchInFile normal execution now shows only replacement text (green), while -WhatIf shows both before (red) and after (green)

Safety:

• Update-LinesInFile now requires -Content when -LineRange is specified
• Newline validation added to Show-TextFile, Update-MatchInFile, Remove-LinesFromFile

Bug Fixes:

• Add-LinesToFile now displays actual insertion line number in summary message

Code Quality

• Reduced code duplication with shared pipeline input handling
• Lazy initialization for content accumulation

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🔧 Technical Details

Newline Validation

Cmdlet	-Pattern	-Contains
Show-TextFile	✅ Error	✅ Error
Update-MatchInFile	✅ Error	✅ Error
Remove-LinesFromFile	✅ Error	✅ Error

Update-LinesInFile Content Behavior

Specification	Intent	Behavior
-Content omitted	Ambiguous	Error (safe default)
-Content @()	Explicit delete	Delete lines
-Content "text"	Replace	Replace with text
-Content ""	Replace with empty	Single empty line

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📄 Installation & Upgrade

# New installation
Install-Module PowerShell.MCP -Force

# Upgrade existing
Update-Module PowerShell.MCP

Update MCP Configuration

1. Get new module path:

(Get-Module PowerShell.MCP).ModuleBase

2. Update claude_desktop_config.json with the path from step 1:

{
  "mcpServers": {
    "PowerShell": {
      "command": "C:\\Users\\YourName\\Documents\\PowerShell\\Modules\\PowerShell.MCP\\1.3.8\\bin\\PowerShell.MCP.Proxy.exe"
    }
  }
}

Note: Adjust path as needed for your environment.

3. Restart Claude Desktop

📖 Full Guide: https://github.com/yotsuda/PowerShell.MCP#quick-start

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Full Documentation: https://github.com/yotsuda/PowerShell.MCP

Questions? GitHub Discussions

Report Issues: GitHub Issues

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⚠ Security Notice: Provides complete PowerShell access. Use in trusted environments only.

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This discussion was created from the release PowerShell.MCP v1.3.8 - Visual -WhatIf Preview for Remove-LinesFromFile & Safety Improvements.