The solution with "commands" did not do anything at all (it only switched off printing "sth changed to a" in gdb) . I think there may be two problems:
1. sth is wrong with gdb (I am using gdb-6.8-r1)
2. I do sth horribly wrong somewhere else while debugging - for example: while setting a breakpoint ;]
the crude solution i used in the first place (by putting additional code inside the program) somehow worked - i have done what i had to do.
But thanks anyway.