GDB’s execution commands have two variants: the normal foreground (synchronous) behavior, and a background (asynchronous) behavior. In foreground execution, GDB waits for the program to report that some thread has stopped before prompting for another command. In background execution, GDB immediately gives a command prompt so that you can issue other commands while your program runs.
If the target doesn’t support async mode, GDB issues an error message if you attempt to use the background execution commands.
To specify background execution, add a
& to the command. For example,
the background form of the
continue command is
c&. The execution commands that accept background execution
Background execution is especially useful in conjunction with non-stop
mode for debugging programs with multiple threads; see Non-Stop Mode.
However, you can also use these commands in the normal all-stop mode with
the restriction that you cannot issue another execution command until the
previous one finishes. Examples of commands that are valid in all-stop
mode while the program is running include
You can interrupt your program while it is running in the background by
Suspend execution of the running program. In all-stop mode,
interrupt stops the whole process, but in non-stop mode, it stops
only the current thread. To stop the whole program in non-stop mode,