Search notes:

where.exe

Find the location of executables.
By default, where.exe searches executables and scripts in directories that are listed in the PATH environment variable. By using /R, it recursively searches for files below the specified directory.
Where is where.exe: 
C:\Users\rene> where where
C:\Windows\System32\where.exe

Notes for using where.exe in PowerShell

There is also a (default) PowerShell alias where for the where-object cmdLet. These two where commands have nothing to do with each other!
While where.exe is able to locate cmd.exe batch files (*.bat), it does not find PowerShell scripts (*.ps1).
However, in PowerShell, the location of a PowerShell script can be found like so 
(get-command script.ps1).source

See also

The shell command which.

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