"Operation not permitted" error when using su

[Stephen Powell <zlinuxman@wowway.com>]

I have discovered a problem recently when using su to switch to a user
other than root on a Gnome Terminal session.  Let's say I login to the
graphical desktop using a userid of "fred".  When I launch a Gnome
Terminal session, I'm automatically logged in as "fred".  Now, let's
suppose I switch to user "barney" by using

   su barney

After entering the password for user "barney", my userid changes to
"barney" in that session.  (whoami reports "barney".)  I then change
to barney's home directory with "cd", issued with no operands.  Now,
certain commands will cause error messages to the terminal.  For example,
if I issue

   vi stuff

Then exit vi with :q, I am back to another shell prompt, but there is an
error message on the screen which looks like this:

   Error: messages not turned on: /dev/pts/0: Operation not permitted

(vi is actually nvi on my system.)
This problem does not occur in a virtual terminal (vt1-vt6).  It also
does not occur if I switch to root, instead of a non-root user.

A search of the internet seemed to suggest that the problem was the
presence of "biff y" in a bash profile.  However, I have looked, and
I cannot find "biff y" specified in any bash-related file.  (I am running
jessie.)  In fact, the biff package is not even installed.  Ideas anyone?

-- 
  .''`.     Stephen Powell    
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