Windows Run Dialog – How Does the Windows Run Dialog Locate Executables?

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When I enter "firefox" in the windows run dialog (i.e. the dialog that appears when you hit windows+R), firefox will launch.

However, "firefox.exe" is not in my %path% because when I type "firefox" in cmd.exe, I get

'firefox' is not recognized as an
internal or external command, operable
program or batch file.

So apparently an executable doesn't need to be found in the windows %path% in order to be discoverable by the run dialog. How does this work?

Best Answer

Apparently the run dialog checks not only the %path% environment variable, but also the "App Path" registry key. From a techrepublic article about the run dialog:

You can launch some third-party applications by typing the name of the executable file in the Open text box and clicking OK—even though the paths to these applications don’t appear in the path environment variable. The reason that this is possible is because the installation procedure for some applications adds the executable file's path to a special registry key called App Paths.

The relevant locations in the registry are HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths and HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\App Paths (this last one being specific to the user). You can add your own "app paths" there with regedit.

For Windows 10/8/7:

Open System Properties (Right click Computer in the start menu, or use the keyboard shortcut Win+Pause)
Click Advanced system settings in the sidebar.
Click Environment Variables...
Select PATH in the System variables section
Click Edit
Add Python's path to the end of the list (the paths are separated by semicolons). For example:
```
C:\Windows;C:\Windows\System32;C:\Python27
```

For Windows XP:

Open System Properties (Type it in the start menu, or use the keyboard shortcut Win+Pause)
Switch to the Advanced tab
Click Environment Variables...
Select PATH in the System variables section
Click Edit
Add Python's path to the end of the list (the paths are separated by semicolons). For example:
```
C:\Windows;C:\Windows\System32;C:\Python27
```
Test on a new terminal window or if using an integrated terminal within a text editor, close and restart your editor or the changes won't be applied.

Windows – What algorithm does the Windows Run Dialog use

Well, the run dialog != the NT command interpretter.

But my guess is that it uses the same algorithm as ShellExecuteEx. I remember an Old New Thing blog post that shows how you could mimic some of the functionality of the Run Dialog box's search by calling the ShellExecute command.

If I was Microsoft, I wouldn't document the search algorithm either. It's an implementation detail.

Best Answer

Related Solutions

Windows – How to Add Python to PATH

For Windows 10/8/7:

For Windows XP:

Windows – What algorithm does the Windows Run Dialog use

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