How to attach a process in gdb

Question

I have a simple C program that forks a process and then runs an executable.

I want to attach the child process to gdb.

I run the main program in a console and open another console to find the pid of the child process, then I start gdb with the following command:

gdb attach 12271

where 12271 is the child process id, but the attach fails with:

No such file or directory.

Any idea why?

Answer 1

Try one of these:

gdb -p 12271
gdb /path/to/exe 12271

gdb /path/to/exe
(gdb) attach 12271