Whats the cmd/powershell equivalent of `which` on bash? [duplicate]

Various.

1. where is a direct equivalent:

   C:\Users\Joey>where cmd
   C:\Windows\System32\cmd.exe
   

   Note that in PowerShell where itself is an alias for Where-Object, thus you need to use where.exe in PowerShell.

2. In cmd you can also use for:

   C:\Users\Joey>for %x in (powershell.exe) do @echo %~$PATH:x
   C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
   

3. In PowerShell you have Get-Command and its alias gcm which does the same if you pass an argument (but also works for aliases, cmdlets and functions in PowerShell):

   PS C:\Users\Joey> Get-Command where
   
   CommandType     Name          Definition
   -----------     ----          ----------
   Alias           where         Where-Object
   Application     where.exe     C:\Windows\system32\where.exe
   

   The first returned command is the one that would be executed.