If you are in, ahem, /directoryb (sorry, but I hate calling directories "folders"), you can call getcwd() to obtain "/directoryb". Since "../directorya/filea" does not start with a /, it must be a relative path. So prepend your current directory to it to get "/directoryb/../directorya/filea" which is an absolute path to the file in question. You could parse this to remove "/.." and the word preceding "/.." if you really need to simplify the path. But no matter what you do, it is possible for files to have multiple absolute paths that do not involve ".." due to symbolic links and loopback mounts.