Create a File Path with Variables in Python

Last Updated : 12 May, 2025

The task is to create a file path using variables in Python. Different methods we can use are string concatenation and os.path.join(), both of which allow us to build file paths dynamically and ensure compatibility across different platforms. For example, if you have a folder named Documents and a file called file.txt, you can create the full file path by combining these variables. This can be done using string concatenation, like folder + "/" + filename, resulting in the path "Documents/file.txt".

Using os.path.join() Method

Python’s os.path.join() function can also be used to handle file paths, as it automatically handles platform-specific path separators (/ for Linux/macOS and \ for Windows).

Python

import os

bp = "/path/to"
fn = "example.txt"

fp = os.path.join(bp, fn)

with open(fp, 'w') as f:
    f.write("Hello, this is an example.")
print("File created successfully")

Output

File created successfully

Explanation:

bp is the base path, and fn is the filename.
fp is the full file path created using os.path.join() to handle platform-specific separators.
The file is opened in write mode ('w'), content is written to it, and the file is saved.

Using f-strings

An f-string is a modern way to concatenate variables in strings. It's quick but does not handle OS-specific separators.

Python

bp = r"/path/to"
fn = "example.txt"

fp = f"{bp}/{fn}"

with open(fp, 'w') as f:
    f.write("Hello, this is an example.")

print("File created successfully using f-string")

Output

File created successfully

Explanation:

The path is built by embedding variables inside a formatted string with / as a separator.
This method assumes the separator is / and does not adapt to OS-specific conventions.

Using pathlib.Path

This method uses the pathlib module's object-oriented path handling for cleaner syntax and cross-platform support.

Python

from pathlib import Path

bp = Path("/path/to")
fn = "example.txt"

fp = bp / fn

with open(fp, 'w') as f:
    f.write("Hello, this is an example.")

print("File created successfully using pathlib.Path")

Explanation:

Path("/path/to") creates a Path object representing a directory.
The / operator is overloaded in pathlib to join paths properly across operating systems.
open() accepts Path objects directly.

Using String Concatenation

One of the simplest methods for building a file path is by concatenating strings. You can concatenate the directory path and file name using the + operator.

Python

bp = r"/path/to"
fn = "example.txt"

fp = bp + "/" + fn

with open(fp, 'w') as f:
    f.write("Hello, this is an example.")
print("File created successfully")

Output

File created successfully

Explanation:

bp is the base path, and fn is the filename.
fp is the full file path created by concatenating bp and fn.
The file is opened in write mode ('w'), and the content is written to it. The file is then saved and closed automatically.