Swap shells between log-ins

shange.sh

# the function is named shange as a play of word for "shell change"
# just run shange if you have it on ~/.profile, /bin or
# both .bashrc and .tcshrc (not sure about the last for I'm not using tcsh)

# only if you are running this as a standalone script (in /bin etc)
# comment the "function shange {" and "}" lines.
function shange {
  if [[ "$(basename $SHELL)" == "bash" ]]; then
    echo "Changing to tcsh"
    chsh -s tcsh
  else
    echo "Changing to bash"
    chsh -s bash
  fi
}