When gdb prompts for input, it annotates this fact so it is possible to know when to send output, when the output from a given command is over, etc.
Different kinds of input each have a different input type. Each
input type has three annotations: a
pre- annotation, which
denotes the beginning of any prompt which is being output, a plain
annotation, which denotes the end of the prompt, and then a
annotation which denotes the end of any echo which may (or may not) be
associated with the input. For example, the
prompt input type
features the following annotations:
^Z^Zpre-prompt ^Z^Zprompt ^Z^Zpost-prompt
The input types are
commandscommand. The annotations are repeated for each command which is input.
set height 0to disable prompting. This is because the counting of lines is buggy in the presence of annotations.