Clean a path name
cleanname [ -d pwd ] names ...
For each file name argument, cleanname, by lexical processing only, prints the shortest equivalent string that names the same (possibly hypothetical) file. It eliminates multiple and trailing slashes, and it lexically interprets . and .. directory components in the name. If the -d option is present, unrooted names are prefixed with pwd/ before processing.
\*9/src/cmd/cleanname.c
cleanname(3).