go-examples/winpath

winpath

An example of getting, setting, and broadcasting PATHs on Windows.

This requires the unsafe package to use a syscall with special message poitners to update PATH without a reboot. It will also build without unsafe.

go build -tags unsafe -o winpath.exe

winpath show

        %USERPROFILE%\AppData\Local\Microsoft\WindowsApps
        C:\Users\me\AppData\Local\Programs\Microsoft VS Code\bin
        %USERPROFILE%\go\bin
        C:\Users\me\AppData\Roaming\npm
        C:\Users\me\AppData\Local\Keybase\

winpath append C:\someplace\special

	Run the following for changes to take affect immediately:
	PATH %PATH%;C:\someplace\special

winpath prepend C:\someplace\special

	Run the following for changes to take affect immediately:
	PATH C:\someplace\special;%PATH%

winpath remove C:\someplace\special

Special Considerations

Giving away the secret sauce right here:

• HWND_BROADCAST
• WM_SETTINGCHANGE

This is essentially the snippet you need to have the HKCU and HKLM Environment registry keys propagated without rebooting:

	HWND_BROADCAST   := uintptr(0xffff)
	WM_SETTINGCHANGE := uintptr(0x001A)
	_, _, err := syscall.
		NewLazyDLL("user32.dll").
		NewProc("SendMessageW").
		Call(HWND_BROADCAST, WM_SETTINGCHANGE, 0, uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr("ENVIRONMENT"))))

• os.Getenv("COMSPEC")
• os.Getenv("SHELL")

If you check SHELL and it isn't empty, then you're probably in MINGW or some such. If that's empty but COMSPEC isn't, you can be reasonably sure that you're in cmd.exe or Powershell.