If rsh doesn't enter a LOGIN entry in the utmp file, login
gets confused and adds a new entry at the end (even if an
entry for the tty already exists). This causes the utmp
file to keep growing as long as the system is up. A utmp
file over 1MB makes "who", "w", and other such programs slow
to a crawl on an active server.
I will send a patch for rsh that makes it create an entry
once I get a bug ID.
See patch in attached email.
This patch has been added to the OpenBSD rsh sources in Raw Hide.
This is an intermediate solution until a PAM module is written
that will manage utmp entries. Thanks for the patch.
And, finally, a better fix (to find utmp entry based on tty slot)
has been put into login.c that makes it unnecessary to create the
utmp entry before exec'ing login. Thanks for pointing this out.
Fix is in util-linux-2.9o-6.