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(gdb.info)Selection

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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 N'
`f N'
     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 `main'.

`frame ADDR'
`f ADDR'
     Select the frame at address 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.

     On the SPARC architecture, `frame' needs two addresses to select
     an arbitrary frame: a frame pointer and a stack pointer.

     On the MIPS and Alpha architecture, it needs two addresses: a stack
     pointer and a program counter.

     On the 29k architecture, it needs three addresses: a register stack
     pointer, a program counter, and a memory stack pointer.

`up N'
     Move N frames up the stack.  For positive numbers N, this advances
     toward the outermost frame, to higher frame numbers, to frames
     that have existed longer.  N defaults to one.

`down N'
     Move N frames down the stack.  For positive numbers N, this
     advances toward the innermost frame, to lower frame numbers, to
     frames that were created more recently.  N defaults to one.  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.  Note:
Printing source lines.

`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.