Finding the path of the program that will execute from the command line in Windows

Use the where command. The first result in the list is the one that will execute.

C:\> where notepad
C:\Windows\System32\notepad.exe
C:\Windows\notepad.exe

According to this blog post, where.exe is included with Windows Server 2003 and later, so this should just work with Vista, Win 7, et al.

On Linux, the equivalent is the which command, e.g. which ssh.

Here's a little cmd script you can copy-n-paste into a file named something like where.cmd:

@echo off
rem - search for the given file in the directories specified by the path, and display the first match
rem
rem    The main ideas for this script were taken from Raymond Chen's blog:
rem
rem         http://blogs.msdn.com/b/oldnewthing/archive/2005/01/20/357225.asp
rem
rem
rem - it'll be nice to at some point extend this so it won't stop on the first match. That'll
rem     help diagnose situations with a conflict of some sort.
rem

setlocal

rem - search the current directory as well as those in the path
set PATHLIST=.;%PATH%
set EXTLIST=%PATHEXT%

if not "%EXTLIST%" == "" goto :extlist_ok
set EXTLIST=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH
:extlist_ok

rem - first look for the file as given (not adding extensions)
for %%i in (%1) do if NOT "%%~$PATHLIST:i"=="" echo %%~$PATHLIST:i

rem - now look for the file adding extensions from the EXTLIST
for %%e in (%EXTLIST%) do @for %%i in (%1%%e) do if NOT "%%~$PATHLIST:i"=="" echo %%~$PATHLIST:i

As the thread mentioned in the comment, get-command in powershell can also work it out. For example, you can type get-command npm and the output is as below: