HP gnu source-level debugger 5992-4701 - Manual (Page 23)

((gdb)) c
Continuing.
define(baz,defn(foo))
baz
0000
Success! The new quotes now work just as well as the default ones. The problem seems
to have been just the two typos defining the wrong lengths. We allow m4 to exit by
giving it an EOF as input:
C-d
Program exited normally.
The message `Program exited normally.' is from GDB; it indicates m4 has finished
executing. We can end our GDB session with the GDB quit command.
((gdb)) quit
1.10 Setting Variable Values During a Session 23