Problem..
A Ctrl-C in a SU started interactive sub-shell terminates the SU session
but does not kill the shell, OR any running command that shell started.
IE it kills the SU, not the running command I am trying to kill.

It also screws up the TTY, so half the commands goes to a sub-program
(if it was running) and leaves the TTY in 'raw' mode, until reset.


Note I start SU, using a command, not a direct login shell.
This allows me to control the environment of the root shell.

I do NOT want to use
    su -m -shell=/bin/bash
As, 1 my shell completely sets up the environment
and 2 I don't want to pass any 'unknown' environment.

New FC5 version   5.96

Using -m -l -s, behaves correctly
  Ctrl-C does not exit shell,  but the logout command does.
  suspend -f   does suspend shell and I can resume the shell.
  But it does not run my shell setup, as environment was NOT preserved.

  /bin/su -m -l -s /bin/bash

  ps xajww
   PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND
  31360 31362 31362 31362 pts/3    31596 Ss     501   0:00
  -bash
  31362 31519 31519 31362 pts/3    31596 S        0   0:00
  /bin/su -m -l -s /bin/bash
  31519 31523 31523 31362 pts/3    31596 S        0   0:00
  -bash
  31523 31596 31596 31362 pts/3    31596 R+       0   0:00
  ps xajfww


Using -m -s, behaves correctly
  It does use my environment, so my Root shell settings are in place, and
  everything else works.  Of course it could pass 'unknown' environment
  settings I did not want to pass to root!

  /bin/su -m -s /bin/bash

   PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND
  31360 31362 31362 31362 pts/3    31728 Ss     501   0:00
  -bash
  31362 31622 31622 31362 pts/3    31728 S        0   0:00
  /bin/su -m -s /bin/bash
  31622 31626 31626 31362 pts/3    31728 S        0   0:00
  bash
  31626 31728 31728 31362 pts/3    31728 R+       0   0:00
  ps xajww

But use a command to start a shell does NOT work.

  /bin/su root -c "exec env PATH=$ROOT_PATH HOME=$ROOT_HOME bash --login";

   PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND

  31360 31362 31362 31362 pts/3    31771 Ss     501   0:00
  -bash
  31362 31771 31771 31362 pts/3    31771 S+       0   0:00
  /bin/su root -c exec env PATH=... HOME=... bash --login
  31771 31774 31774 31774 ?           -1 Ss       0   0:00
  bash --login
  31774 31928 31928 31774 ?           -1 R        0   0:00
  ps xajww

  Now Ctrl-C kills the su...
     Session terminated, killing shell... ...killed.
  But any sub-commands continue to run, and terminal settings have been
  screwwed up, with half the characters going to the sub-program
  and half to the prompt.

  As you can see the SID and TPGID changed in this case!

  SU does not do this under FC4, or on any other UNIX machine I have
  previously used.

  Removing the -login makes no difference, except make bash run
  ".bash_profile", rather than ".bashrc" in the home it is using.

Old FC4  version  5.2.1

  Run under FC5 does not behave the same as on FC4 either.

  This shows that the problem may not be a SU problem but some library problem.