Python breakpoint debugging on the command line with pdb
Setting breakpoints on the command line is usually done with a debugging tool. The following is an example of how Python uses pdb to debug breakpoints on the command line.
1. Import the pdb module
In Python scripts, you can import the pdb module and add the pdb.set_trace() statement at the point where you want a breakpoint. This will automatically enter the pdb debugger when you run into that statement.
For example, add the following statement to the script code to set a breakpoint:
import pdb # Add the following statement at the location where the breakpoint needs to be set pdb.set_trace()
2. Run the script
Run the script by entering the following command at the command line:
python
where is the name of the script file to run.
3. Enter the pdb debugger
When the program runs topdb.set_trace() statement, you are automatically entered into the pdb debugger. At this point, you can use a number of commands to check the status of the program, such asn command to execute the next line of code, the s command to enter the function, thec command to continue executing the program, etc.
In the pdb debugger, you can also view the value of a variable, for example, by typing the name of the variable to see its current value.
4. Exit the pdb debugger
In the pdb debugger, enterq command to exit the debugger and stop program execution.
Note: Some Python IDEs (e.g., PyCharm) have an integrated pdb debugger, so you can set breakpoints and debug directly in the IDE, which is more convenient.
python basic breakpoint debugging pdb module easy to use
preamble
Breakpoint debugging is the foundation of the program. pdb is a debugger that comes with Python that helps us set breakpoints in our code and provides commands to help us debug the program as it executes.
In-code use of
Here are some ways to use the pdb module:
Setting breakpoints in code: Use the pdb.set_trace() function to set breakpoints where you want to pause program execution. For example
import pdb
def my_func():
x = 5
pdb.set_trace() # Set breakpoints
y = x + 3
print(y)
my_func()When the program executes to pdb.set_trace(), it pauses and waits for your command.
pdb commands: While the program is paused, you can use pdb's commands to view variables, execute code, and so on. Here are some commonly used commands:
n: Execute the next line of code.
c: Continue executing the code until the next breakpoint.
s: executes the current line and goes inside the current function.
l: displays the code around the current line.
p : Displays the value of the variable.
q: Exit the pdb debugger.
For example, you can use the p command to see the value of a variable when the program is paused:
> /path/to/(5)my_func() -> y = x + 3 (Pdb) p x 5
Command Line Usage
You can also use pdb on the command line to execute Python scripts and enter debug mode. Example:
python -m pdb my_script.py
This starts the Python interpreter and puts it into pdb debug mode while the my_script.py file is being executed.
pdb is a very powerful debugger that can help us quickly locate problems in our code. However, its use requires some experience and skill. When you encounter code that is difficult to debug, consider using pdb to help you find the problem.
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