rename - rename a file
integer function rename (from, to)
character*(*) from, to
From must be the pathname of an existing file. To will become the new
pathname for the file. If to exists, then both from and to must be the
same type of file, and must reside on the same filesystem. If to
exists, it will be removed first.
The returned value will be 0 if successful; a system error code other-
Pathnames can be no longer than MAXPATHLEN as defined in <sys/param.h>.
4th Berkeley Distribution 18 July 1983 RENAME(3F)