Claude Code Pwsh Guard

claude-code-pwsh-guard

A Claude Code hook pack that catches bash-only shell syntax before it reaches a Windows PowerShell session, and either rewrites it to the PowerShell equivalent or blocks it with the correct command in the error message.

Claude                                                    pwsh-guard                          Result
──────────────────────────────────────────────────────────────────────────────────────────────────
Bash("shopt -s extglob;                       ─▶  PreToolUse: deny                   ✗ never runs
      rm -f !(keep.txt|keep2.txt)")               [ERROR] shopt / extglob is a bash builtin
                                                   PowerShell: Get-ChildItem -Exclude ... |
                                                               Remove-Item
                                                  [ERROR] extglob pattern !(...)

Bash("Get-ChildItem -Exclude                  ─▶  (silent)                            ✓ runs
      keep.txt,keep2.txt | Remove-Item")

Bash("export NODE_ENV=production;             ─▶  PreToolUse: allow + updatedInput    ✓ runs, fixed
      echo $PATH > /dev/null")                    $env:NODE_ENV = "production";
                                                  echo $env:PATH > $null

Without the guard, that first command produces `The term 'shopt' is not recognized`, Claude tries a variation of the same bash syntax, and the loop repeats. That loop is [issue #28670](https://github.com/anthropics/claude-code/issues/28670).

   

Quick start

1. Clone this repo anywhere: git clone https://github.com//claude-code-pwsh-guard
2. cd claude-code-pwsh-guard
3. powershell -ExecutionPolicy Bypass -File .\install.ps1