windows-shell

Windows Shell Skill

This skill provides guidelines for handling Windows filesystem paths and commands to avoid common pitfalls when using Claude Code on Windows.

Core Principles

Path Formats

In Skills and Configuration:

• Always use forward slashes (Unix-style): scripts/helper.py
• Never use backslashes in Skills: scripts\helper.py
• This ensures cross-platform compatibility

In Bash Commands:

• Always quote paths with spaces or backslashes: cd "C:\KolyaRepositories\project"
• Without quotes, backslashes are lost: cd C:\KolyaRepositories\project
• Result: /usr/bin/bash: line 1: cd: C:KolyaRepositoriesproject: No such file or directory

Shell Command Patterns

Good patterns:

# Quoted paths work reliably
cd "C:\KolyaRepositories\repo" && git status

# Multiple commands in sequence
cd "C:\KolyaRepositories\repo" && git rev-parse --abbrev-ref HEAD && git status --short

# Direct git commands without piping
git status --short

Bad patterns:

# Unquoted paths fail
cd C:\KolyaRepositories\repo && git status

# Piping to findstr after cd fails
cd "C:\KolyaRepositories\repo" && git status --short | findstr /R "."
# Error: FINDSTR: Cannot open repo

# PowerShell via -Command loses cd context
cd "C:\KolyaRepositories\repo" && powershell -Command "git status --short | Where-Object { $_ }"
# Error: The term 'C:\KolyaRepositories\repo' is not recognized

Common Pitfalls

1. Findstr After Directory Change

Problem: findstr interprets the directory name as a file argument when piped after cd.

# Fails
cd "C:\KolyaRepositories\calc" && git status --short | findstr /R "."
# Error: FINDSTR: Cannot open calc

Solution: Use direct commands without unnecessary pipes.

# Works
cd "C:\KolyaRepositories\calc" && git status --short

2. PowerShell Context Loss

Problem: Using powershell -Command after cd causes the shell context to be misinterpreted.

# Fails
cd "C:\KolyaRepositories\calc" && powershell -Command "git status --short | Where-Object { $_ }"
# Error: The term 'C:\KolyaRepositories\calc' is not recognized

Solution: Either use PowerShell directly from the start, or avoid PowerShell piping after bash cd.

# Works - all in PowerShell
powershell -Command "cd 'C:\KolyaRepositories\calc'; git status --short"

# Works - no PowerShell piping
cd "C:\KolyaRepositories\calc" && git status --short

3. Unquoted Paths in Bash

Problem: Bash strips backslashes from unquoted Windows paths.

# Fails
cd C:\KolyaRepositories\calc
# Error: cd: C:KolyaRepositoriescalc: No such file or directory

Solution: Always quote paths containing backslashes.

# Works
cd "C:\KolyaRepositories\calc"

4. Output Redirection to Null Device

Context: Claude Code uses Git Bash on Windows, which provides Unix-like paths.

In Git Bash (Claude Code default):

# CORRECT - Git Bash provides /dev/null
command > /dev/null 2>&1

# WRONG - creates a literal file named "nul" in working directory!
command >nul 2>&1

WARNING: Using >nul in Git Bash creates a file that pollutes git status. Always use /dev/null in Git Bash.

In PowerShell:

command 2>$null
command | Out-Null

5. PowerShell Special Character Escaping

Problem A - Negation Operator: When passing PowerShell commands via Bash, the exclamation mark character gets escaped to backslash-exclamation.

# Fails - ! becomes \!
powershell -Command "if (!(Test-Path 'file.txt')) { Write-Output 'missing' }"
# Error: \! is not recognized

Solution: Use -not instead of exclamation mark for negation.

# Works
powershell -Command "if (-not (Test-Path 'file.txt')) { Write-Output 'missing' }"

Problem B - Variable Interpolation: PowerShell $variable syntax gets stripped when passed through Bash.

# Fails - $pdf and $sizeKB are empty
powershell -Command "$pdf = Get-Item 'file.pdf'; $sizeKB = [math]::Round($pdf.Length / 1KB, 1); Write-Output $sizeKB"
# Output: (empty or partial)

Solution: Use .ps1 script files for complex operations, or pipe output between simple commands.

# Works - use script file
powershell -ExecutionPolicy Bypass -File "script.ps1" -Path "file.pdf"

# Works - simple piped commands
powershell -Command "Get-Item 'file.pdf' | Select-Object Length"

Summary for inline PowerShell:

• Use -not instead of exclamation mark
• Use script files for complex logic with variables
• Keep inline commands simple (single operation, pipe output)

Best Practices for Multi-Repo Operations

When iterating over multiple repositories (e.g., for status checks):

Pattern 1 - Sequential commands with &&:

cd "C:\KolyaRepositories\repo1" && git status --short
cd "C:\KolyaRepositories\repo2" && git status --short

Pattern 2 - Self-contained commands:

git -C "C:\KolyaRepositories\repo1" status --short
git -C "C:\KolyaRepositories\repo2" status --short

Pattern 3 - Parallel tool calls: Use multiple Bash tool calls in a single message for independent operations:

• Bash tool 1: cd "C:\repo1" && git status
• Bash tool 2: cd "C:\repo2" && git status
• Bash tool 3: cd "C:\repo3" && git status

PowerShell vs Bash on Windows

When to Use PowerShell

Use PowerShell for:

• Windows-specific operations (registry, services, etc.)
• Complex filtering with Where-Object, Select-Object
• Working with .NET objects
• Windows system administration tasks

# PowerShell example
powershell -Command "Get-ChildItem -Path 'C:\KolyaRepositories' -Directory | Select-Object Name"

When to Use Bash (Git Bash/WSL)

Use Bash for:

• Git operations
• Standard Unix tools (grep, sed, awk)
• Cross-platform scripts
• Most development tooling (npm, docker, etc.)

# Bash example
cd "C:\KolyaRepositories\repo" && git status --short

Tools to Prefer Over Bash

For file operations, use specialized Claude Code tools instead of bash commands:

Operation	Use Tool	Not Bash
Read files	Read tool	cat, head, tail
Search files	Glob tool	find, ls
Search content	Grep tool	grep, rg
Edit files	Edit tool	sed, awk
Write files	Write tool	echo >, cat <<EOF

Reserve Bash for actual terminal operations: git, npm, docker, build commands, etc.

Summary Checklist

Before running Windows filesystem commands:

• Paths with backslashes are quoted: "C:\Path\To\Dir"
• Using /dev/null for output redirection in Git Bash (NOT >nul which creates a file)
• No unnecessary pipes after cd (especially findstr, Where-Object)
• Using specialized tools (Read, Glob, Grep) instead of bash for file ops
• Multiple independent operations use parallel tool calls
• Skills use forward slashes: scripts/helper.py
• PowerShell used for Windows-specific tasks, Bash for Unix-style operations
• Using -not instead of exclamation mark for PowerShell negation
• Complex PowerShell logic in .ps1 files, not inline commands

Examples from Real Errors

Common Error Patterns:

1. findstr after cd → FINDSTR: Cannot open [dirname]
2. PowerShell pipe after cd → The term 'C:...' is not recognized
3. Unquoted path → cd: C:KolyaRepositories... (backslashes stripped)
4. Using >nul in Git Bash → creates a literal file named "nul" polluting git status
5. Using exclamation mark in PowerShell via Bash → backslash-exclamation is not recognized
6. Inline $variable in PowerShell → variables are empty/stripped

Resolution: All resolved by following the patterns in this skill:

• Quote paths: cd "C:\KolyaRepositories\repo"
• Avoid pipes after cd: git status --short (no | findstr)
• Use /dev/null in Git Bash: command > /dev/null 2>&1 (NOT >nul)
• Use -not instead of exclamation mark for negation
• Use .ps1 script files for complex PowerShell logic