how to get /r and /m in /etc/motd

My /etc/motd has both \r and \m in it, but it is printed verbatim on
login.  I'm guessing that these are `uname -r` and `uname -m`, but if I
put those in the motd, even with the backquotes, it is still printed
verbatim.  Since the out-of-the-box RH distrtibution has \r and \m in
the /etc/motd (or /etc/issue; I don't recall) there must be a way to get
them expanded to their actual values.  Has anyone managed to do this?

-- 
Christopher Barnard
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comment your code as if the maintainer will be a homicidal maniac who
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