POSTIN

/bin/sh

for s in /bin/ksh /bin/rksh /usr/bin/ksh /usr/bin/rksh 
do
  if [ ! -f /etc/shells ]; then
        echo "$s" > /etc/shells
  else
        if ! grep -q '^'"$s"'$' /etc/shells ; then
                echo "$s" >> /etc/shells
        fi
  fi
done

/bin/systemctl try-restart systemd-binfmt.service >/dev/null 2>&1 || :

POSTUN

/bin/sh

for s in /bin/ksh /bin/rksh /usr/bin/ksh /usr/bin/rksh 
do
  if [ ! -f $s ]; then
     sed -i '\|^'"$s"'$|d' /etc/shells
  fi
done