Powershell script to locate specific file/file name?

From a powershell prompt, use the gci cmdlet (alias for Get-ChildItem) and -filter option:

gci -recurse -filter "hosts"

This will return an exact match to filename "hosts".

SteveMustafa points out with current versions of powershell you can use the -File switch to give the following to recursively search for only files named "hosts" (and not directories or other miscellaneous file-system entities):

gci -recurse -filter "hosts" -File 

The commands may print many red error messages like "Access to the path 'C:\Windows\Prefetch' is denied.".

If you want to avoid the error messages then set the -ErrorAction to be silent.

gci -recurse -filter "hosts" -File -ErrorAction SilentlyContinue

An additional helper is that you can set the root to search from using -Path. The resulting command to search explicitly search from, for example, the root of the C drive would be

gci -Recurse -Filter "hosts" -File -ErrorAction SilentlyContinue -Path "C:\"

Assuming you have a Z: drive mapped:

Get-ChildItem -Path "Z:" -Recurse | Where-Object { !$PsIsContainer -and [System.IO.Path]::GetFileNameWithoutExtension($_.Name) -eq "hosts" }

I use this form for just this sort of thing:

gci . hosts -r | ? {!$_.PSIsContainer}

. maps to positional parameter Path and "hosts" maps to positional parameter Filter. I highly recommend using Filter over Include if the provider supports filtering (and the filesystem provider does). It is a good bit faster than Include.