gdb: Selection
8.3 Selecting a Frame
=====================
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.
'frame [ FRAME-SELECTION-SPEC ]'
'f [ FRAME-SELECTION-SPEC ]'
The 'frame' command allows different stack frames to be selected.
The FRAME-SELECTION-SPEC can be any of the following:
'NUM'
'level NUM'
Select frame level NUM. 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 level
frame is usually the one for 'main'.
As this is the most common method of navigating the frame
stack, the string 'level' can be omitted. For example, the
following two commands are equivalent:
(gdb) frame 3
(gdb) frame level 3
'address STACK-ADDRESS'
Select the frame with stack address STACK-ADDRESS. The
STACK-ADDRESS for a frame can be seen in the output of 'info
frame', for example:
(gdb) info frame
Stack level 1, frame at 0x7fffffffda30:
rip = 0x40066d in b (amd64-entry-value.cc:59); saved rip 0x4004c5
tail call frame, caller of frame at 0x7fffffffda30
source language c++.
Arglist at unknown address.
Locals at unknown address, Previous frame's sp is 0x7fffffffda30
The STACK-ADDRESS for this frame is '0x7fffffffda30' as
indicated by the line:
Stack level 1, frame at 0x7fffffffda30:
'function FUNCTION-NAME'
Select the stack frame for function FUNCTION-NAME. If there
are multiple stack frames for function FUNCTION-NAME then the
inner most stack frame is selected.
'view STACK-ADDRESS [ PC-ADDR ]'
View a frame that is not part of GDB's backtrace. The frame
viewed has stack address STACK-ADDR, and optionally, a program
counter address of PC-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.
When viewing a frame outside the current backtrace using
'frame view' then you can always return to the original stack
using one of the previous stack frame selection instructions,
for example 'frame level 0'.
'up N'
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.
'down N'
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 'down' as 'do'.
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.
For example:
(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 'edit'. 
Printing Source Lines List, for
details.
'select-frame [ FRAME-SELECTION-SPEC ]'
The '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. The FRAME-SELECTION-SPEC is as for
the 'frame' command described in Selecting a Frame
Selection.
'up-silently N'
'down-silently N'
These two commands are variants of 'up' and 'down', 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
distracting.
Info Catalog
gdb: Backtrace
gdb: Stack
gdb: Frame Info