safecat is an implementation of D. J. Bernstein's maildir algorithm.
It can be used to write mail messages to a qmail-style maildir, or to
write data to a "spool" directory reliably. There are no lockfiles with
safecat, and nothing is left to chance. If safecat returns a successful
exit status, then you can be (practically) 100% sure your data is
safely committed to disk. Further, if data is written to a directory
using safecat (or other implementations of the maildir algorithm),
then every file in that directory is guaranteed to be complete. If
safecat fails to write all of the data, there will be no file at all
in the destination directory.
