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

Answer 1

With a running instance of myExecutableName having a PID 15073:

hitting Tab twice after $ gdb myExecu in the command line, will automagically autocompletes to:

$ gdb myExecutableName 15073

and will attach gdb to this process. That's nice!

Answer 2

The first argument should be the path to the executable program. So

gdb progname 12271

Answer 3

Try one of these:

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

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