Can I use GDB to debug a running process?

Question

Under linux, can I use GDB to debug a process that is currently running?

Answer 1

Easiest way is to provide the process id.

gdb -p `pidof your_running_program_name`

Please get the full list of option in man gdb command.

In case there are multiple process for the same program running, then the following command will list the processes.

ps -C program -o pid h
<number>

Then the output process id (number) can be used as argument to gdb.

gdb -p <process id>

Answer 2

Yes you can. Assume a process foo is running...

ps -elf | grep foo

look for the PID number

gdb -a {PID number}