INTRODUCING THE HP-UX SYMBOLIC DEBUGGER, CDB

        What is a debugger?

            It's a special  program that is used to find and  understand
            run-time errors (bugs) in other  programs.  It allows you to
            run a buggy program under close control, pausing it, setting
            breakpoints,  examining  and  changing its memory, etc.  For
            interpreted languages like BASIC, the debugger is built into
            the human interface.  For compiled  languages, such as C, HP
            FORTRAN, and Pascal on HP-UX, it is a separate program.

        What is a symbolic debugger?

            It's a debugger  which  "knows" the symbols  (procedure  and
            variable  names) used in the source code which was  compiled
            to make the  program.  You can ask for data  values by name,
            not by address, in the same way they are  referenced  in the
            source  code.  It may also  "know"  the source  lines of the
            program, so you can refer to program  locations by procedure
            name and line number, not by address.

        Why is cdb a good symbolic debugger?

            It has a rich  feature set, much more than just the basics a
            symbolic debugger might offer.

            It is  multi-lingual,  supporting  C, HP FORTRAN, and Pascal
            (invoked as cdb, fdb, or pdb).  It has a good  understanding
            of the data  types used by the three  languages,  and has an
            almost complete  expression  handler built in.  You can dump
            complete  data  structures  easily.  There are a variety  of
            display formats for looking at things in different ways.

            You can call procedures from the debugger  command line, and
            you can  declare  and use  local  (debugger)  variables.  It
            "knows"  your  source  code and even  helps you  search  for
            patterns.  It has a powerful capability called  "assertions"
            for tracking down hard-to-locate bugs.

            You can store a command list with a breakpoint or assertion.
            The debugger  supports  record and playback of commands, and
            recording  of all  debugger  output.  Like most  interactive
            HP-UX  programs,  it provides a "shell  escape",  so you can
            call other  HP-UX  programs  without  leaving the  debugger.
            There is an on-line quick reference guide built in, too.