I asked Jeff Korn (David Korn's son), who in turn asked David Korn who confirmed that 'read -u' comes from ksh and that 'u' stands for 'unit'.
- Dan C.
Hey, did your dad do `read -u`?---------- Forwarded message ----------
From: Doug McIlroy <doug@cs.dartmouth.edu>
Date: Tue, May 31, 2016 at 3:27 AM
Subject: [TUHS] etymology of read -u
To: tuhs@minnie.tuhs.org
What's the mnmonic significance, if any, of the u in
the bash builtin read -u for reading from a specified
file descriptor? Evidently both f and d had already been
taken in analogy to usage in some other commands.
The best I can think of is u as in "tape unit", which
was common usage back in the days of READ INPUT TAPE 5.
That would make it the work of an old timer, maybe Dave Korn?