Python Check If File Exists

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Python Check If File Exists

Summary: in this tutorial, you’ll learn how to check if a file exists.

When processing files, you’ll often want to check if a file exists before doing something else with it such as reading from the file or writing to it.

To do it, you can use the exists() function from the os.path module or is_file() method from the Path class in the pathlib module.

os.path.exists() function

from os.path import exists

file_exists = exists(path_to_file)

Code language: JavaScript (javascript)

Path.is_file() method

from pathlib import Path

path = Path(path_to_file)

path.is_file()

Code language: JavaScript (javascript)

1) Using os.path.exists() function to check if a file exists

To check if a file exists, you pass the file path to the exists() function from the os.path standard library.

First, import the os.path standard library:

import os.path

Code language: JavaScript (javascript)

Second, call the exists() function:

os.path.exists(path_to_file)

Code language: CSS (css)

If the file exists, the exists() function returns True. Otherwise, it returns False.

If the file is in the same folder as the program, the path_to_file is just simply the file name.

However, it’s not the case, you need to pass the full file path of the file. For example:

/path/to/filename

 

Even if you run the program on Windows, you should use the forward-slash (/) to separate the path. It’ll work across Windows, macOS, and Linux.

The following example uses the exists() function to check if the readme.txt file exists in the same folder as the program:

import os.path

file_exists = os.path.exists('readme.txt')

print(file_exists)

Code language: JavaScript (javascript)

If the readme.txt file exists, you’ll see the following output:

True

Code language: PHP (php)

Otherwise, you’ll see False on the screen:

False

Code language: PHP (php)

To make the call to the exists() function shorter and more obvious, you can import that function and rename it to file_exists() function like this:

from os.path import exists as file_exists

file_exists('readme.txt')

Code language: JavaScript (javascript)

2) Using the pathlib module to check if a file exists

Python introduced the pathlib module since the version 3.4.

The pathlib module allows you to manipulate files and folders using the object-oriented approach. If you’re not familiar with object-oriented programming, check out the Python OOP section.

First, import the Path class from the pathlib module:

from pathlib import Path

Code language: JavaScript (javascript)

Then, instantiate a new instance of the Path class and initialize it with the file path that you want to check for existence:

path = Path(path_to_file)

 

Finally, check if the file exists using the is_file() method:

path.is_file()

Code language: CSS (css)

If the file doesn’t exist, the is_file() method returns False. Otherwise, it returns True.

The following example shows how to use the Path class from the pathlib module to check if the readme.txt file exists in the same folder of the program:

from pathlib import Path

path_to_file = 'readme.txt'
path = Path(path_to_file)

if path.is_file():
print(f'The file {path_to_file} exists')
else:
print(f'The file {path_to_file} does not exist')

Code language: PHP (php)

If the readme.txt file exists, you’ll see the following output:

The file readme.txt exists

Code language: CSS (css)

Summary

  • Use os.path.exists() function or Path.is_file() method to check if a file exists

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