from DESCR:
safecat is a program which implements D. J. Bernstein's
maildir algorithm to copy stdin safely to a file in a speci-
fied directory. With safecat, the user is offered two assur-
ances. First, if safecat returns a successful exit status,
then all data is guaranteed to be saved in the destination
directory. Second, if a file exists in the destination
directory, placed there by safecat, then the file is guaran-
teed to be complete.
