====== functions ======


[[https://www.gnu.org/software/make/manual/html_node/File-Name-Functions.html|8.3 Functions for File Names]]

  * $(**dir** /path/to/file.txt) - get path part only
  * $(**notdir** src/foo.c hacks) - result ''foo.c hacks''. 
  * $(**suffix** ...)
  * $(**basename** src/foo.c src-1.0/bar hacks) - produces the result ''src/foo src-1.0/bar hacks''. 
  * $(**addsuffix**)
  * $(**addprefix**)
  * $(**join**)
  * $(**wildcard**)
  * $(**realpath**) - NOTE: file must exist!
  * $(**abspath**) - NOTE: do not require file to exist