Debugging Python with pdb

Oct 27, 2023 · 2 min.
Cheet sheet

Use pdb to debug python code. Cheat sheet.

python

Part of the Beginner's Guide series:

  1. Git Command Guide
  2. Coding Python in Linux Server
  3. Create A Site by Hugo
  4. Using tmux to manage your terminal
  5. Tensorboard Cheet Sheet (SummaryWriter)
  6. Debugging Python with pdbThis post!
  7. Customize your PyTorch Dataset
  8. Cheetsheet for Python os module

Cheat sheet for debugging python code with pdb.

Start pdb Link to this heading

python
1import pdb
2pdb.set_trace()

This command will create a breakpoint in your code. When the code reaches this point, it will stop and you will be able to debug it. The cmd line will look like this:

bash
1(Pdb) # here you can type commands, or check the value of variables

pdb commands Link to this heading

Check the source code Link to this heading

bash
1(Pdb) l # list 11 lines of code around the current line
bash
1(Pdb) ll # list the whole function

Step next Link to this heading

Command Description
n step next (will not go into functions)
s step into (will go into functions)
r step out (will go out of functions)

Check variables Link to this heading

bash
1(Pdb) p <variable> # print the value of a variable

Actually, you can use any python code here, for example:

bash
1(Pdb) p [x for x in range(10)] # print a list

p is not necessary, you can just type the code and it will be executed.

Other commands Link to this heading

Command Description
c continue execution (will stop at the next breakpoint)
q quit the debugger (will stop the execution)
a print the argument list of the current function
whatis <variable> print the type of a variable

References Link to this heading