Description:

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.

Of course, you know that such a thing cannot be: between UNIX and the different
hardware options available, a 100% guarantee is not possible. However, safecat
takes every precaution possible in writing your data.