movefile - change name of a file
int movefile (from,to);
Movefile attempts to change the name of the file from to to.
Movefile uses link(2) and unlink(2) if possible, since this is the
fastest way to change the name of a file. Under certain
circumstances (i.e. if from and to specify different mounted
devices), this may fail; in such a case, movefile will creat(2) the
result file and use filecopy(3) to copy the data.
If movefile is successful, then
from will be deleted and movefile
will return a 0. If unsuccessful, to will be deleted (if any file
already has this name), and -1 will be returned.
mv(1), link(2), unlink(2), creat(2), filecopy(3)
Returns 0 normally; -1 on error. If an error occurs, from still