Demonstrate use of sessions with bash in org babel.

* Simple command, set a variable

  Get basics about the shell, etc.  Set a varable

#+begin_src bash :exports both :results output :session TEST
date
echo SHELL is $SHELL
echo BASH_VERSION is $BASH_VERSION
echo PID is $$
SET_IN_FIRST_BLOCK=something
#+end_src

#+RESULTS:
: Wed Nov 16 07:45:29 AM EST 2022
: SHELL is /bin/bash
: BASH_VERSION is 5.1.16(1)-release
: PID is 73788

* Simple command, read variable set

  Get pid. Should be same as previous example.

  See if the variable exists

#+begin_src bash :exports both :results output :session TEST
date
echo PID is $$
[[ -v SET_IN_FIRST_BLOCK ]] && \
    echo SET_IN_FIRST_BLOCK is $SET_IN_FIRST_BLOCK || \
        echo SET_IN_FIRST_BLOCK is not defined
#+end_src

#+RESULTS:
: Wed Nov 16 07:45:32 AM EST 2022
: PID is 73788
: > > SET_IN_FIRST_BLOCK is something


* Setup - Don't ask about resetting the session

  Pay no attention to that man behind the curtain.

  This is emacs lisp foo that turn of prompting when killing the
  buffer running the shell.

#+BEGIN_SRC elisp
  (setq kill-buffer-query-functions
    (remq 'process-kill-buffer-query-function
           kill-buffer-query-functions))
#+END_SRC

#+RESULTS:

* Reset the session :results output

  Kill the TEST session.   Variables, PID should reset.

  https://emacs.stackexchange.com/questions/5293/how-to-force-an-org-babel-session-to-reset-or-initialize
  #+begin_src bash :exports both :results output :session  (if (get-buffer "TEST") (if (kill-buffer "TEST") (print "TEST") (print "TEST")) (print "TEST"))

  PS1="$ "
  date
  echo TEST session killed
  echo PID is $$

  [[ -v SET_IN_FIRST_BLOCK ]] && \
    echo SET_IN_FIRST_BLOCK is $SET_IN_FIRST_BLOCK || \
        echo SET_IN_FIRST_BLOCK is not defined
  #+end_src

  #+RESULTS:
  :
  : gmj@mx:$ Wed Nov 16 07:45:39 AM EST 2022
  : TEST session killed
  : PID is 73860
  : gmj@mx:$ > > SET_IN_FIRST_BLOCK is not defined