Basics of Working with gdb

gdb has a command-line interface similar to a Unix shell. You type a command and then press the Enter key to execute it. If you have never worked with gdb before, begin by executing the help command, which produces the following output:

     List of classes of commands:
     aliases -- Aliases of other commands
     breakpoints -- Making program stop at certain points
     data -- Examining data
     files -- Specifying and examining files
     internals -- Maintenance commands
     obscure -- Obscure features
     running -- Running the program
     stack -- Examining the stack
     status -- Status inquiries
     support -- Support facilities
     tracepoints -- Tracing of program execution without stopping the program
     user-defined -- User-defined commands
     Type "help" followed by a class name for a list of commands in that class.
     Type "help" followed by command name for full documentation.
     Command name abbreviations are allowed if unambiguous.

The instructions in the preceding output give you a starting point from which you
can continue a more in-depth study of gdb. For example, if you want to learn about
how to run a program being debugged, execute help running, which in turn gives you
the following:

     Running the program.
     List of commands:
     advance -- Continue the program up to the given location (same form as args for break
     command)
     attach -- Attach to a process or file outside of GDB
     continue -- Continue program being debugged
     detach -- Detach a process or file previously attached
     disconnect -- Disconnect from a target
     finish -- Execute until selected stack frame returns
     handle -- Specify how to handle a signal
     info handle -- What debugger does when program gets various signals
     interrupt -- Interrupt the execution of the debugged program
     jump -- Continue program being debugged at specified line or address
     kill -- Kill execution of program being debugged
     next -- Step program
     nexti -- Step one instruction
     run -- Start debugged program
     set args -- Set argument list to give program being debugged when it is started
     set environment -- Set environment variable value to give the program
     set follow-fork-mode -- Set debugger response to a program call of fork or vfork
     set scheduler-locking -- Set mode for locking scheduler during execution
     set step-mode -- Set mode of the step operation
     show args -- Show argument list to give program being debugged when it is started
     show follow-fork-mode -- Show debugger response to a program call of fork or vfork
     show scheduler-locking -- Show mode for locking scheduler during execution
     show step-mode -- Show mode of the step operation
     signal -- Continue program giving it signal specified by the argument
     step -- Step program until it reaches a different source line
     stepi -- Step one instruction exactly
     target -- Connect to a target machine or process
     thread -- Use this command to switch between threads
     thread apply -- Apply a command to a list of threads
     apply all -- Apply a command to all threads
     tty -- Set terminal for future runs of program being debugged
     unset environment -- Cancel environment variable VAR for the program
     until -- Execute until the program reaches a source line greater than the current
     Type "help" followed by command name for full documentation.
     Command name abbreviations are allowed if unambiguous.

Now you have a list of commands, related to running a program, to learn. Suppose
you want to learn about the run command. Execute help run. The following output is
produced:

       Start debugged program. You may specify arguments to give it.
       Args may include "*", or "[...]"; they are expanded using "sh".
       Input and output redirection with ">", "<", or ">>" are also allowed.
       With no arguments, uses arguments last specified (with "run" or "set args").
       To cancel previous arguments and run with no arguments,
       use "set args" without arguments.

Using the preceding method, you can get a full listing of gdb commands and learn about each one. If you prefer reading the manual, it is available at http:://www.gnu.org/ software/gdb/documentation.
Table 2-4 is a list of commands that you may find particularly useful when studying the MySQL source. Note the abbreviated version column. Using abbreviated versions significantly speeds up the tasks even if you are a fast typist.