CommandFixer

A lightweight Go binary that auto-corrects your common typing mistakes in PowerShell before commands execute.

Type git sattus, press Enter and CommandFixer silently swaps it for git status - then runs it, if you approve.

Works in both PowerShell 7 (pwsh) and Windows PowerShell 5 (powershell.exe).

Who it is for and who it is not for

It is for someone who lives in PowerShell on Windows and mistypes the same handful of commands often enough to want them corrected in place. Suggestions arrive through a PSReadLine hook and nothing is rewritten behind your back: you confirm before the corrected command runs.

It is not a shell, not a replacement for tab completion and not a command generator. It matches against a database of common CLI tools using a similarity threshold, so it corrects spelling rather than intent: it will turn a misspelt command into the one you meant to type, never a wrong command into the right one. It works by hooking PowerShell profiles on Windows and has no meaning outside that environment.

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Quick Start

1. Build

git clone https://github.com/oernster/commandfixer
cd commandfixer
.\build.ps1 -Test        # run tests then build

Or with go directly:

go build -o commandfixer.exe .

2. Install

.\install.ps1

The installer:

• Copies commandfixer.exe to %LOCALAPPDATA%\CommandFixer\
• Adds that directory to your user PATH
• Copies config.example.json to %USERPROFILE%\.typo-fixer\config.json
• Hooks into your PowerShell profile for both PS7 and PS5

Then restart PowerShell (both pwsh and powershell.exe will have the hook).

3. Uninstall

.\uninstall.ps1

The uninstaller:

• Removes the hook from both PS7 (Documents\PowerShell\profile.ps1) and PS5 (Documents\WindowsPowerShell\profile.ps1)
• Removes the binary from %LOCALAPPDATA%\CommandFixer\
• Removes that directory from your user PATH
• Keeps your config and log at %USERPROFILE%\.typo-fixer\ (data is yours)

To also delete config and log:

.\uninstall.ps1 -RemoveConfig

Then restart PowerShell to complete removal.

You can also uninstall via the binary directly (if it is on your PATH):

commandfixer uninstall   # removes profile hooks only; does not touch binary or PATH

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Reinstall / Upgrade

To upgrade to a new build (or reinstall after code changes), rebuild and re-run the installer. install.ps1 is idempotent: it overwrites the existing binary with -Force, leaves your PATH entry and your config/log untouched and refreshes the PowerShell profile hook for both PS7 and PS5.

.\build.ps1 -Test        # rebuild commandfixer.exe (runs tests first)
.\install.ps1            # overwrite the installed binary and refresh the hook

Then restart PowerShell so the new binary is picked up.

For a clean reinstall that also resets your config and log, uninstall with -RemoveConfig first, then install:

.\uninstall.ps1 -RemoveConfig
.\build.ps1
.\install.ps1

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4. Configure

There is nothing you have to configure. Corrections come from a database built into the binary, so it is useful the moment it is installed.

If you want to tune it, edit %USERPROFILE%\.typo-fixer\config.json:

{
  "settings": {
    "log_file": "",
    "max_log_lines": 10000,
    "similarity_threshold": 0.6
  }
}

similarity_threshold is how close a typo must be to a known command before it is offered, in the range (0.0, 1.0]. Lower catches more typos and starts offering corrections you did not want. log_file empty means the default location below.

5. Use It

Type any misconfigured command and press Enter:

PS> git sattus
CommandFixer: did you mean: git status [Y/n]
On branch main ...

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How It Works

CommandFixer hooks into PSReadLine (built into both PowerShell 7 and Windows PowerShell 5) and intercepts the Enter key. When you press Enter:

1. PSReadLine captures the current buffer.
2. It calls commandfixer suggest <your-command>.
3. CommandFixer fuzzy-matches it against a built-in database of CLI tools, their subcommands and the standard Windows commands and prints a suggestion when one is close enough. Nothing is printed when it has nothing to offer.
4. If there is a suggestion, PowerShell shows it and waits for you to confirm.
5. The corrected command executes only if you accept it.

No system-wide keyboard hooks. No persistent service required. The binary runs in milliseconds.

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CLI Commands

commandfixer suggest <cmd>       Fuzzy-match and print correction (used by hook)
commandfixer correct <cmd>       Like suggest but also logs the correction
commandfixer log <from> <to>     Record a correction you accepted (used by hook)
commandfixer install [profile]   Add PSReadLine hook to your profile(s)
commandfixer uninstall [profile] Remove the hook from your profile(s)
commandfixer stats               Show correction count and rule breakdown
commandfixer version             Print version
commandfixer help                Show help

Without a [profile] argument, install and uninstall target both PS7 and PS5 profiles simultaneously.

Manual correction check

commandfixer correct "git sattus"
# Prints: git status

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Files

Path	Purpose
%USERPROFILE%\.typo-fixer\config.json	Settings: log location and match sensitivity
%USERPROFILE%\.typo-fixer\corrections.log	JSONL corrections log
%LOCALAPPDATA%\CommandFixer\commandfixer.exe	Installed binary
Documents\PowerShell\profile.ps1	PS7 profile (hook appended here)
Documents\WindowsPowerShell\profile.ps1	PS5 profile (hook appended here)

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Further Reading

• DEVELOPMENT.md - build steps, local dev workflow, debugging
• ARCHITECTURE.md - system design, module breakdown, data flow
• TESTING.md - testing strategy, coverage requirements, how to run tests
• TECH_DEBT.md - what is still open, what is deliberately left and what only looks like debt