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User-defined command hooks
You may define "hooks", which are a special kind of user-defined
command. Whenever you run the command `foo', if the user-defined
command `hook-foo' exists, it is executed (with no arguments) before
A hook may also be defined which is run after the command you
executed. Whenever you run the command `foo', if the user-defined
command `hookpost-foo' exists, it is executed (with no arguments) after
that command. Post-execution hooks may exist simultaneously with
pre-execution hooks, for the same command.
It is valid for a hook to call the command which it hooks. If this
occurs, the hook is not re-executed, thereby avoiding infinte recursion.
In addition, a pseudo-command, `stop' exists. Defining
(`hook-stop') makes the associated commands execute every time
execution stops in your program: before breakpoint commands are run,
displays are printed, or the stack frame is printed.
For example, to ignore `SIGALRM' signals while single-stepping, but
treat them normally during normal execution, you could define:
handle SIGALRM nopass
handle SIGALRM pass
handle SIGLARM pass
As a further example, to hook at the begining and end of the `echo'
command, and to add extra text to the beginning and end of the message,
you could define:
(gdb) echo Hello World
You can define a hook for any single-word command in GDB, but not
for command aliases; you should define a hook for the basic command
name, e.g. `backtrace' rather than `bt'. If an error occurs during
the execution of your hook, execution of GDB commands stops and GDB
issues a prompt (before the command that you actually typed had a
chance to run).
If you try to define a hook which does not match any known command,
you get a warning from the `define' command.
Created Mon Nov 8 17:42:39 2004 on tillpc with info_to_html version 0.9.6.