2.1 Invoking gdb
Invoke gdb by running the program
gdb. Once started,
gdb reads commands from the terminal until you tell it to exit.
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 here are designed to cover a variety of situations; in some environments, some of these options may effectively be unavailable.
The most usual way to start gdb is with one argument, specifying an executable program:
You can also start with both an executable program and a core file specified:
gdb program core
You can, instead, specify a process ID as a second argument, if you want to debug a running process:
gdb program 1234
would attach 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. gdb will warn you if it is unable to attach or to read core dumps.
You can optionally have
gdb pass any arguments after the
executable file to the inferior using
--args. This option stops
gdb --args gcc -O2 -c foo.c
This will cause
gdb to debug
gcc, and to set
gcc's command-line arguments (see Arguments) to -O2 -c foo.c.
You can run
gdb without printing the front material, which describes
gdb's non-warranty, by specifying
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 (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 the -x option is used.