i'm running gdb with attach on a process how do i halt the continuing i'm stuck there

Question

hi i'm pretty much using gdb for the first time, i tried looking at the internet for info about my prob but i could not find.

i run

$gdb

then i'm running

attach <mypid>

then i see that my process is stuck (which is probably ok) now i want it to continue running so i run

continue

and my process continues running but from here i'm stuck if i want again to watch my current stack trace etc how do i do that i couldnt get out of continuing... i tried 'ctrl-d' etc nothing worked for me... (was just a guess).

thanks...

Answer 1

Control+C in the gdb process should bring you back to the command prompt.

Answer 2

Here's a short GDB tutorial, and here's a full GDB manual.

The point of debugging is to inspect interesting/suspicious parts of the program. Breakpoints allow you to stop execution at some source location, and watchpoints allow you to stop when interesting data changes.

Simple examples:

(gdb) break my_function
(gdb) cont

This will insert a breakpoint at the beginning of my_function, so when execution of the program enters the function the program will be suspended and you get GDB prompt back, and be able to inspect program's state. Or you can step through the code.

(gdb) watch my_var
(gdb) cont

Same, but not the program will be stopped at whatever location that modifies the value of my_var.

Shameless plug - here's a link to my GDB presentation at NYC BSD User Group. Hope this helps.