I have been trying to use pdb to debug my Python program, however whenever I get to this screen

enter image description here

I don't know what to do. Usually when I use pdb I just type commands after (Pdb), but when I try to do the same in the buffer above like

(Pdb) n

It gives me "n is undefined" in the minibuffer. I've tried to look at tutorials for using pdb in emacs specifically such as here and here, but I still can't figure out where to type the commands. When I used an IDE I just typed the commands like I tried above, but here it doesn't seem to work. I'm sure the solution must be obvious, but any help is appreciated.

  • You are trying to run pdb as a compilation process... the buffer created by M-x compile or similar is typically read-only, so typing anything into it will not result in changing the text of the buffer. How did you get to running pdb in this way? I normally just run my Python scripts from shell with python -m pdb script.py [script arguments], but there should also be a way to run it from GUD.
    – wvxvw
    Dec 20, 2017 at 8:35
  • 1
    Also, take a look at this project: github.com/realgud/realgud it seems to have nice integration with PDB.
    – wvxvw
    Dec 20, 2017 at 8:42
  • 1
    Ok thanks, I didn't know that you can't run pdb by compiling. I think I tried using the shell before but I got stuck with that too, but It seems that using C-c C-p and then C-c C-c along with import pdb; pdb.set_trace() works. I was confused since I thought C-c C-p would run the program, but it seems that it only starts the Python process. I also tried realgud but I also couldn't seem to get that to work. I suppose I will have to chalk that up to new user error since I am still learning how this whole thing works. Thanks for the help. Dec 20, 2017 at 21:08

1 Answer 1


Not quite sure where you're at with this but the following works for me:

M-x pdb

It prompts for your program file and starts the debugger.

I didn't have pdb installed on my system so I had to create this (from here ... it also has a windows version)

cat > ~/bin/pdb << EOF
exec python -m pdb "$@"
chmod +x ~/bin/pdb

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