|Debugging with GDB: Selection|
Most commands for examining the stack and other data in your program work on whichever stack frame is selected at the moment. Here are the commands for selecting a stack frame; all of them finish by printing a brief description of the stack frame just selected.
Select frame number n. Recall that frame zero is the innermost
(currently executing) frame, frame one is the frame that called the
innermost one, and so on. The highest-numbered frame is the one for
frame stack-addr [ pc-addr ]
f stack-addr [ pc-addr ]
Select the frame at address stack-addr. This is useful mainly if the chaining of stack frames has been damaged by a bug, making it impossible for GDB to assign numbers properly to all frames. In addition, this can be useful when your program has multiple stacks and switches between them. The optional pc-addr can also be given to specify the value of PC for the stack frame.
Move n frames up the stack; n defaults to 1. For positive numbers n, this advances toward the outermost frame, to higher frame numbers, to frames that have existed longer.
Move n frames down the stack; n defaults to 1. For
positive numbers n, this advances toward the innermost frame, to
lower frame numbers, to frames that were created more recently.
You may abbreviate
All of these commands end by printing two lines of output describing the frame. The first line shows the frame number, the function name, the arguments, and the source file and line number of execution in that frame. The second line shows the text of that source line.
(gdb) up #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) at env.c:10 10 read_input_file (argv[i]);
After such a printout, the
list command with no arguments
prints ten lines centered on the point of execution in the frame.
You can also edit the program at the point of execution with your favorite
editing program by typing
See Printing Source Lines,
select-frame command is a variant of
frame that does
not display the new frame after selecting it. This command is
intended primarily for use in GDB command scripts, where the
output might be unnecessary and distracting.
These two commands are variants of
respectively; they differ in that they do their work silently, without
causing display of the new frame. They are intended primarily for use
in GDB command scripts, where the output might be unnecessary and