This command is useful if you want to debug a core dump instead of a running process. GDB ignores any core dump file while your program is running.
The kill command is also useful if you want to recompile and relink your program. With BlackBerry 10 OS, it's possible to modify an executable file while it's running in a process. If you want to run the new version, kill the current process; when you next type run, GDB notices that the file has changed, and reads the symbol table again (while trying to preserve your current breakpoint settings).