Here are some notes about shell traps:

= syntax =
 * 'trap' - show a list of active trap handlers
 * 'trap -l' - show a list of possible signals to trap (doesn't include ERR and EXIT)
 * 'trap "<handler command>" <signal> [<signal2>...]' - set trap handler to indicated command
 * 'trap - <signal> [<signal2]' - reset trap handler to default


= notes =
 * with set -e, and an ERR handler set, the error handler runs, but the script still exits
   * when err_handler exits, the script does it's EXIT routine

 * entering a function clears the ERR trap handler
   * fixable with "set -o errtrace"
 * I can't seem to get traptest.sh to respond to SIGTERM