That's for PowerShell, not DOS. IIRC, for DOS you could do something like "dir /s *.txt" to list all files with .txt extension in all subdirectories of the current directory, so "dir /s x" would be somewhat equivalent to Unix's "find -name x" (not as fast as "locate x", but should return the same if run on the root directory, and if there were no changes since the locate database was last rebuilt).