Some sources for UNIX/Linux history:

*   Chapter 1 of the course text

*   http://www.bell-labs.com/history/unix/philosophy.html
*   http://www.bell-labs.com/history/unix/
*   http://www.linux.org/article/view/what-is-linux

BSD - Berkeley Software Distribution

...

POSIX - Portable Operating System Interface

*   family of standards
*   specified by the IEEE
*   purpose is maintain compatibility
    between operating systems,

    defining the Application Programming 
    Interface (API)
    along with command-line shells and
    utility interfaces, for software 
    compatibility with variants of UNIX
    and other operating systems

*   POSIX.2, one of this family of
    standards, is a standard for user
    commands, and the text uses this
    standard;
    ...ideally, this should mean that
    UNIX systems from different sources
    and on different machines
    should be more consistent on the
    command-line level if they are
    POSIX.2 compliant...

*   some common shells -
    Korn Shell (ksh)
    Bourne shell (sh)
    C shell (csh)
    GNU Bourne-again shell (bash)