ftp/rcp can't copy devices

[Chris Torek]

In article <779 at philmds.UUCP> hulsebos at philmds.UUCP (Rob Hulsebos) writes:
>When I use the 'ftp' or 'rcp' command, and want to copy a disk-partition
>(accessed via /dev/rdsk/*) to the other end, both utilities
>complain: "not a plain file".
>
>Of course, the manual doesn't mention that only plain files can be
>transferred. Does anybody know why ftp and rcp behave this way?

Both attempt to determine the size of the file before sending it.
(Only rcp's protocol actually requires this.)  There is no way to
find the size of a special file without reading it, and in the process
the data may vanish (e.g., reading /dev/tty or a socket).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris