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Invoking GDB
Invoke GDB by running the program gdb. Once started, GDB reads commands from the terminal until you tell it to
quit.
You can also run
gdb with a variety of arguments and options, to specify more of your debugging
environment at the outset.
The command-line options described in the following discussions are designed
to cover a variety of situations; in some environments, effectively, some of
these options may be unavailable.
The most usual way to start GDB is with one argument, specifying an executable
program that you want to debug.
gdb program
You can also start with both an executable program and a core file specified
as the following example’s input and variables show.
gdb program core
You can, instead, specify a process ID as a second argument, if you want to
debug a running process, for instance, as the following example’s input and
variables show.
gdb program 1234
Your machine hereby attaches GDB to process 1234 (unless you also have a file named ‘1234’; GDB does check for a core file first).
Taking advantage of the second command-line argument requires a fairly
complete operating system; when you use GDB as a remote debugger attached to a bare
board, there may not be any notion of process, and there is often no way to get a core dump.
You can run
gdb without printing the front material, which describes GDB’s non-warranty, by
specifying -silent:
gdb -silent
You can further control how GDB starts up by using command-line options. GDB
itself can remind you of the options available.
To display all available options and briefly describe their use, use
gdb -help as input (‘gdb -h’ is a shorter equivalent).
All options and command line arguments you give are processed in sequential
order. The order makes a difference when using the ‘
-x’ option.