Is there an equivalent of 'which' on the Windows command line?

Windows Server 2003 and later (i.e. anything after Windows XP 32 bit) provide the where.exe program which does some of what which does, though it matches all types of files, not just executable commands. (It does not match built-in shell commands like cd.) It will even accept wildcards, so where nt* finds all files in your %PATH% and current directory whose names start with nt.

Try where /? for help.

Note that Windows PowerShell defines where as an alias for the Where-Object cmdlet, so if you want where.exe, you need to type the full name instead of omitting the .exe extension. Alternatively, you can set an alias for it:

Set-Alias which where.exe

Update: Using Get-Command (alias: gcm) is recommended since it's native to PS and will get all command types: aliases, cmdlets, executables, and functions. Example:

gcm notepad*

While later versions of Windows have a where command, you can also do this with Windows XP by using the environment variable modifiers, as follows:

c:\> for %i in (cmd.exe) do @echo.   %~$PATH:i
   C:\WINDOWS\system32\cmd.exe

c:\> for %i in (python.exe) do @echo.   %~$PATH:i
   C:\Python25\python.exe

You don't need any extra tools and it's not limited to PATH since you can substitute any environment variable (in the path format, of course) that you wish to use.

And, if you want one that can handle all the extensions in PATHEXT (as Windows itself does), this one does the trick:

@echo off
setlocal enableextensions enabledelayedexpansion

:: Needs an argument.

if "x%1"=="x" (
    echo Usage: which ^<progName^>
    goto :end
)

:: First try the unadorned filenmame.

set fullspec=
call :find_it %1

:: Then try all adorned filenames in order.

set mypathext=!pathext!
:loop1
    :: Stop if found or out of extensions.

    if "x!mypathext!"=="x" goto :loop1end

    :: Get the next extension and try it.

    for /f "delims=;" %%j in ("!mypathext!") do set myext=%%j
    call :find_it %1!myext!

:: Remove the extension (not overly efficient but it works).

:loop2
    if not "x!myext!"=="x" (
        set myext=!myext:~1!
        set mypathext=!mypathext:~1!
        goto :loop2
    )
    if not "x!mypathext!"=="x" set mypathext=!mypathext:~1!

    goto :loop1
:loop1end

:end
endlocal
goto :eof

:: Function to find and print a file in the path.

:find_it
    for %%i in (%1) do set fullspec=%%~$PATH:i
    if not "x!fullspec!"=="x" @echo.   !fullspec!
    goto :eof

It actually returns all possibilities but you can tweak it quite easily for specific search rules.

Under PowerShell, Get-Command will find executables anywhere in $Env:PATH.

$ Get-Command eventvwr

CommandType   Name          Definition
-----------   ----          ----------
Application   eventvwr.exe  c:\windows\system32\eventvwr.exe
Application   eventvwr.msc  c:\windows\system32\eventvwr.msc

And since powershell let's you define aliases, which can be defined like so.

$ sal which gcm   # short form of `Set-Alias which Get-Command`
$ which foo
...

PowerShell commands are not just executable files (.exe, .ps1, etc). They can also be cmdlets, functions, aliases, custom executable suffixes set in $Env:PATHEXT, etc. Get-Command is able to find and list all of these commands (quite akin to Bash's type -a foo). This alone makes it better than where.exe, which.exe, etc which are typically limited to finding just executables.

Finding executables using only part of the name

$ gcm *disk*

CommandType     Name                             Version    Source
-----------     ----                             -------    ------
Alias           Disable-PhysicalDiskIndication   2.0.0.0    Storage
Alias           Enable-PhysicalDiskIndication    2.0.0.0    Storage
Function        Add-PhysicalDisk                 2.0.0.0    Storage
Function        Add-VirtualDiskToMaskingSet      2.0.0.0    Storage
Function        Clear-Disk                       2.0.0.0    Storage
Cmdlet          Get-PmemDisk                     1.0.0.0    PersistentMemory
Cmdlet          New-PmemDisk                     1.0.0.0    PersistentMemory
Cmdlet          Remove-PmemDisk                  1.0.0.0    PersistentMemory
Application     diskmgmt.msc                     0.0.0.0    C:\WINDOWS\system32\diskmgmt.msc
Application     diskpart.exe                     10.0.17... C:\WINDOWS\system32\diskpart.exe
Application     diskperf.exe                     10.0.17... C:\WINDOWS\system32\diskperf.exe
Application     diskraid.exe                     10.0.17... C:\WINDOWS\system32\diskraid.exe
...

Finding custom executables

Unlike UNIX, where executables are files with the executable (+x) bit set, executables on windows are files present in one of the directories specified in the $PATH env. variable whose filename suffixes are named in the $PATHEXT env. variable (defaults to .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC;.CPL).

As Get-Command also honours this env. variable, it can be extended to list custom executables. e.g.

$ $Env:PATHEXT="$Env:PATHEXT;.dll;.ps1;.psm1;.py"     # temporary assignment, only for this shell's process

$ gcm user32,kernel32,*WASM*,*http*py

CommandType     Name                        Version    Source
-----------     ----                        -------    ------
ExternalScript  Invoke-WASMProfiler.ps1                C:\WINDOWS\System32\WindowsPowerShell\v1.0\Invoke-WASMProfiler.ps1
Application     http-server.py              0.0.0.0    C:\Users\ME\AppData\Local\Microsoft\WindowsApps\http-server.py
Application     kernel32.dll                10.0.17... C:\WINDOWS\system32\kernel32.dll
Application     user32.dll                  10.0.17... C:\WINDOWS\system32\user32.dll

See Get-Command for more options and examples.

In Windows PowerShell:

set-alias which where.exe