files on standard input as an mtree(8) `specfile' specification, and
write or copy only those items in the specfile.
If the file exists in the underlying file system, its permissions and
modification time will be used unless specifically overridden by the
specfile. An error will be raised if the type of entry in the specfile
conflicts with that of an existing file.
Otherwise, it is necessary to specify at least the following parameters
in the specfile: type, mode, gname or gid, and uname or uid, device
(in the case of block or character devices), and link (in the case of
symbolic links). If time isn't provided, the current time will be used.
