# Find the longest correct path within a given path

proc CorrectPath {path} {
	set correctPath "/"
	foreach fileName [file split $path] {
		set testedPath $correctPath
		lappend testedPath $fileName 
		if [file isdirectory [file join $testedPath]] {
			set correctPath $testedPath
		} else {
			break
		}
	}
	return $correctPath
}

puts [CorrectPath "/ftp/aux"]