Throughout the book we’ve seen a variety of ways in which the shell
processes input lines, especially using
read. We can think of this process as a subset of
the things the shell does when processing command lines. This appendix
provides a more detailed description of the steps involved in processing the
command line and how you can get bash to make a second
pass with eval. The material in this Appendix A also appears in Learning the bash
Shell by Cameron Newham (O’Reilly).