---
title: "7 Need to Know Python pdb Debugger Commands"
description: "Here are the seven top python pdb commands. Helpful to use these commands at the pdb command line. Each one is explained with the result."
url: https://srinimf.com/2022/03/07/7-need-to-know-python-pdb-debugger-commands/
date: 2022-03-07
modified: 2026-10-10
author: "Srini"
image: https://i0.wp.com/srinimf.com/wp-content/uploads/2022/03/pexels-photo-7014925.jpeg?fit=1880%2C1253&ssl=1
categories: ["Python"]
tags: ["pdb debugger commands"]
type: post
lang: en
---

# 7 Need to Know Python pdb Debugger Commands

Here are seven helpful python pdb commands. Those are next, quit, print line numbers, display variable, set break points and clear break points.

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## Here’s Python source code to use for debugging

```
#Python source code is present # in main.py
import pdb; 
pdb.set_trace() 

#try finally 
try: 
    print("Hello World") 
    # No luck, an exception 
    number = int("abc") 
finally: 
    print("==> Let's start our journey to the moon!") 

print("TO THE MOON…")
```

Before you [start debugging](https://pymotw.com/2/pdb/), firstly import pdb. Then set pdb to set_trace(). The set_trace() allows you [to debug your](https://srinimf.com/2021/07/30/ibm-debugger-here-are-the-most-useful-commands/) code interactively.

## List of python pdb commands

n –> to go to next stmt

q —> to quit from debug mode

l —> to print line numbers

p –> display variable

b—> b x set b point

cl –> clear

c –> continue

## Result of each command of pdb debugger

### Python pdb Command n

Here, you will see the result of ‘n’ command. It goes to next statement and execute it.

```
> /home/repl/b7e783ae-efe2-4425-ac87-ed04cfce52d6/main.py(5)<module>() 
-> try: 
(Pdb) 
n 
> /home/repl/b7e783ae-efe2-4425-ac87-ed04cfce52d6/main.py(6)<module>() 
-> print("Hello World") 
(Pdb)
```

### Python pdb Command q

You will see here the result of ‘q’ command. The control comes out of the debugger.

```
> /home/repl/ef97b988-d2f3-44b5-97f5-c83110b99b76/main.py(5)<module>() 
-> try: 
(Pdb) 
q 
Traceback (most recent call last): 
  File "main.py", line 5, in <module> 
    try: 
  File "main.py", line 5, in <module> 
    try: 
  File "/usr/lib/python3.8/bdb.py", line 88, in trace_dispatch 
    return self.dispatch_line(frame) 
  File "/usr/lib/python3.8/bdb.py", line 113, in dispatch_line 
    if self.quitting: raise BdbQuit 
bdb.BdbQuit 


** Process exited - Return Code: 1 **
```

### Python pdb Commands l (print line numbers) and c (continue)

The command l displays line numbers for source code.

```
> /home/repl/6b3c467d-30ac-477f-ab1e-fe07b185a710/main.py(5)<module>() 
-> try: 
(Pdb) 
l 
  1  	import pdb; 
  2  	pdb.set_trace() 
  3  	 
  4  	#try finally 
  5  ->	try: 
  6  	    print("Hello World") 
  7  	    # No luck, an exception 
  8  	    number = int(123) 
  9  	finally: 
 10  	    print("==> Let's start our journey to the moon!") 
 11  	 
(Pdb) 
c 
Hello World 
==> Let's start our journey to the moon! 
TO THE MOON… 


** Process exited - Return Code: 0 **
```

### Python Command p

The command p and variable name if you give, it displays the value present in the variable.

```
> /home/repl/46fca557-3b61-4079-9d94-cec3d6789312/main.py(5)<module>() 
-> try: 
(Pdb) 
n 
> /home/repl/46fca557-3b61-4079-9d94-cec3d6789312/main.py(6)<module>() 
-> print("Hello World") 
(Pdb) 
n 
Hello World 
> /home/repl/46fca557-3b61-4079-9d94-cec3d6789312/main.py(8)<module>() 
-> number = int(123) 
(Pdb) 
n 
> /home/repl/46fca557-3b61-4079-9d94-cec3d6789312/main.py(10)<module>() 
-> print("==> Let's start our journey to the moon!") 
(Pdb) 
p number 
123 
(Pdb) 
c 
==> Let's start our journey to the moon! 
TO THE MOON… 


** Process exited - Return Code: 0 **
```

### Command b (break point) and Command cl (clears all break points)

Here, when you set b and line number, it sets break point at that line. The cl command clears all break points. I set break point at line 8. When I give c (continue), it will then stops at line 8.

```
> /home/repl/cb23d974-ca23-4158-bef1-c16f7f9b0183/main.py(5)<module>() 
-> try: 
(Pdb) 
l 
  1  	import pdb; 
  2  	pdb.set_trace() 
  3  	 
  4  	#try finally 
  5  ->	try: 
  6  	    print("Hello World") 
  7  	    # No luck, an exception 
  8  	    number = int(123) 
  9  	finally: 
 10  	    print("==> Let's start our journey to the moon!") 
 11  	 
(Pdb) 
b 8 
Breakpoint 1 at /home/repl/cb23d974-ca23-4158-bef1-c16f7f9b0183/main.py:8 
(Pdb) 
c 
Hello World 
> /home/repl/cb23d974-ca23-4158-bef1-c16f7f9b0183/main.py(8)<module>() 
-> number = int(123) 
(Pdb)
```

### Python Clear cl command

```
> /home/repl/5124e49f-df43-456e-a356-1509a51a127e/main.py(5)<module>() 
-> try: 
(Pdb) 
b 8 
Breakpoint 1 at /home/repl/5124e49f-df43-456e-a356-1509a51a127e/main.py:8 
(Pdb) 
c 
Hello World 
> /home/repl/5124e49f-df43-456e-a356-1509a51a127e/main.py(8)<module>() 
-> number = int(123) 
(Pdb) 
cl 
Clear all breaks? 
y 
Deleted breakpoint 1 at /home/repl/5124e49f-df43-456e-a356-1509a51a127e/main.py:8 
(Pdb) 
c 
==> Let's start our journey to the moon! 
TO THE MOON… 


** Process exited - Return Code: 0 ** 
Press Enter to exit terminal
```

To sum up, these seven commands are useful to work with python pdb debugger.

References

- [How To Use the Python Debugger](https://www.digitalocean.com/community/tutorials/how-to-use-the-python-debugger)
- [The python debugger-pdb](https://docs.python.org/3/library/pdb.html)

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