c - How to monitor variables in GDB and log it if it meets certain conditions?

Question

I would like to know if there is any way in which I can monitor a value of a variable until for example a counter reaches a value and then log the output of variable value during each counter value?

Answer 1

Set a watch point on the counter:

(gdb) watch var

And make that watchpoint conditional:

(gdb) cond <watchpoint_number> var>=value

If you want to log to a file:

(gdb) set logging file <filename>
(gdb) set logging on

By default gdb logs to gdb.txt