Break Commands

Go forward to Breakpoint Menus
Go backward to Conditions
Go up to Breakpoints
Go to the top op gdb

Breakpoint command lists

You can give any breakpoint (or watchpoint or catchpoint) a series of
commands to execute when your program stops due to that breakpoint.  For
example, you might want to print the values of certain expressions, or
enable other breakpoints.
`commands [BNUM]'
`... COMMAND-LIST ...'
     Specify a list of commands for breakpoint number BNUM.  The
     commands themselves appear on the following lines.  Type a line
     containing just `end' to terminate the commands.
     To remove all commands from a breakpoint, type `commands' and
     follow it immediately with `end'; that is, give no commands.
     With no BNUM argument, `commands' refers to the last breakpoint,
     watchpoint, or catchpoint set (not to the breakpoint most recently
   Pressing <RET> as a means of repeating the last GDB command is
disabled within a COMMAND-LIST.
   You can use breakpoint commands to start your program up again.
Simply use the `continue' command, or `step', or any other command that
resumes execution.
   Any other commands in the command list, after a command that resumes
execution, are ignored.  This is because any time you resume execution
(even with a simple `next' or `step'), you may encounter another
breakpoint--which could have its own command list, leading to
ambiguities about which list to execute.
   If the first command you specify in a command list is `silent', the
usual message about stopping at a breakpoint is not printed.  This may
be desirable for breakpoints that are to print a specific message and
then continue.  If none of the remaining commands print anything, you
see no sign that the breakpoint was reached.  `silent' is meaningful
only at the beginning of a breakpoint command list.
   The commands `echo', `output', and `printf' allow you to print
precisely controlled output, and are often useful in silent
breakpoints.  *Note Commands for controlled output: Output.
   For example, here is how you could use breakpoint commands to print
the value of `x' at entry to `foo' whenever `x' is positive.
     break foo if x>0
     printf "x is %d\n",x
   One application for breakpoint commands is to compensate for one bug
so you can test for another.  Put a breakpoint just after the erroneous
line of code, give it a condition to detect the case in which something
erroneous has been done, and give it commands to assign correct values
to any variables that need them.  End with the `continue' command so
that your program does not stop, and start with the `silent' command so
that no output is produced.  Here is an example:
     break 403
     set x = y + 4