ensureFileSuffix(fileName, suffix, strip = NULL)
expandFileName(fileName, base = getwd())
relativePath(path, referencePath)fileName.suffix. The intended suffix does not need to be given here, as the function will not append it if the specified file name already has the correct suffix.fileName is a relative path, this option gives the base directory which the path is relative to. If fileName is an absolute path, this argument is ignored.ensureFileSuffix function returns the specified file names with the requested suffixes appended. expandFileName returns the full path to the specified file name, collapsing ".." elements if appropriate. relativePath returns the specified path, expressed relative to referencePath.J.D. Clayden, S. Muñoz Maniega, A.J. Storkey, M.D. King, M.E. Bastin & C.A. Clark (2011). TractoR: Magnetic resonance imaging and tractography with R. Journal of Statistical Software 44(8):1-18.
path.expand performs some of what expandFileName does.