When you issue the run command, your program begins to execute immediately. See Chapter 5 for discussion of how to arrange for your program to stop. Once your program has stopped, you may call functions in your program, using the print or call commands. See Chapter 8.
If the modification time of your symbol file has changed since the last time the debugger read its symbols, the debugger discards its symbol table, and reads it again. When it does this, the debugger tries to retain your current breakpoints.