Debugging with GDB (September 2007)

Chapter 20: GDB Annotations 257
20 GDB Annotations
This chapter describes annotations in GDB. Annotations are designed to interface GDB
to graphical user interfaces or other similar programs which want to interact with GDB at
a relatively high level.
20.1 What is an annotation?
To produce annotations, start GDB with the --annotate=2 option.
Annotations start with a newline character, two ‘control-z’ characters, and the name
of the annotation. If there is no additional information assoc iated with this annotation,
the name of the annotation is followed immediately by a newline. If there is additional
information, the name of the annotation is followed by a space, the additional information,
and a newline. The additional information cannot contain newline characters.
Any output not beginning with a newline and two ‘control-z’ characters denotes literal
output from GDB. Currently there is no need for GDB to output a newline followed by two
‘control-z’ characters, but if there was such a need, the annotations could be extended
with an ‘escape’ annotation which means those three characters as output.
A simple example of starting up GDB with annotations is:
$ gdb --annotate=2
GNU GDB 5.0
Copyright 2000 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it
under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty"
for details.
This GDB was configured as "sparc-sun-sunos4.1.3"
^Z^Zpre-prompt
(gdb)
^Z^Zprompt
quit
^Z^Zpost-prompt
$
Here ‘quit’ is input to GDB; the rest is output from GDB. The three lines beginning
‘^Z^Z’ (where ‘^Z’ denotes a ‘control-z’ character) are annotations; the rest is output from
GDB.
20.2 The server prefix
To issue a command to GDB without affecting certain aspects of the state which is
seen by users, prefix it with ‘server ’. This means that this command will not affect the
command history, nor will it affect GDB’s notion of which command to repeat if
h
RET
i
is
pressed on a line by itself.