watch points et al...

[Hassan Aurag <aurag at cae dot com>]

Hi all,

I am currently trying to figure out how to make gdb (or write extension
etc...) watch a variable without interrupting the program.

My case is that of a realtime program that I do not want to interrupt. It's
running on a standard RedHat Linux distro at a certain frequency.

My goal is to see if I can do the following:

1- Watch the value of a variable in some file as the program runs (and plot
it eventually). The variables are Fortran vars, so they are static. But no
interruption to the program, except for the overhead generated from watching
the variable.
2-  Injecting/replacing code without recompilation/reloading (simple stuff
though, not 2000 liners). A typical case would be replacing 'x=y*z + t' with
'x=3*z' or 'x=3' etc....

I have been looking for something that would let me do this in gdb to no
avail. Any idea about how I could use gdb or an interface to gdb to do this?
Any examples out there? 

Thanks in advance