Python os.path.join: A Beginner’s Guide

The Python os.path.join method combines one or more path names into a single path. This method is often used with os methods like os.walk() to create the final path for a file or folder. os.path.join() automatically adds any required forward slashes into a file path name.

How to Use Python os.path.join

You may have gotten caught up in a path labyrinth when you’re working with files in Python.

To work with files, you need to specify the directory in which a file appears. This is easier than it sounds. If you don’t specify the right path, your program will not work.

In this guide, we’re going to talk about os.path.join. This is a method that combines components of a file path into a complete path. We’ll walk through two examples to help you get started with this method.

What is in a File Path?

A file path is a sequence of file and folder names. This sequence of names takes you to a certain place on your computer’s operating system (OS).

Let’s take the following path as an example:

/Users/James/tutorials

This path takes us to a folder called “tutorials”. If we wanted to access a particular file or directory in this folder, we could point to it using its file name:

/Users/James/tutorials/README.md

You can write these file paths manually in Python. Doing so can be impractical. That’s where os.path.join comes in.

What is Python os.path.join?

os.path.join combines path names into one complete path. This means that you can merge multiple parts of a path into one, instead of hard-coding every path name manually.

To use this function, you need to import the os library into your code:

import os

Let’s take a look at the syntax of the os.path.join() method. The os.path.join function accepts a list of paths that you want to merge into one:

os.path.join(path1, path2...)

path1, path2, and all subsequent values represent the paths you want to combine into a single name.

path = os.path.join("/Users/James/tutorials", "index.html")
print(path)

This code returns: /Users/James/tutorials/index.html. The os.path.join method continues from the absolute path component we have specified (“/Users/James/tutorials”). We add index.html to the end of the path.

Handily, the os.path.join method inserts forward slashes (which are called “directory separators”) when they are needed. This makes it a more convenient way of combining file path names than manually concatenating them.

os.path.join Python Example

Let’s write combine the file name “index.html” in the folder “tutorials/web/”. This file is inside our current working directory.

We’ll start by importing the os library:

import os

Next, we are going to get our current working directory so that we can add our file path name to it:

cwd = os.getcwd()

This returns our current working directory, which is /Users/James/tutorials. The “tutorials” folder is inside our user’s home directory. We can use this information to add “tutorials/web” to the end of our working directory:

web_tutorials = os.path.join(cwd, "tutorials/web")
print(web_tutorials)

This code returns: /Users/James/tutorials/web. Our code has combined our path name components into one. A forward slash (“/”) has been added between our path names. This path refers to the “web” folder in our existing path.

Python os.path.join: List Files

Let’s use the os.path.join method to return the full file paths of all the files in a folder. We’re going to list all the files in the “Desktop” folder on our file system. This folder is located in the “/Users/James/” directory on the drive.

We’ll start by importing the os library and defining the directory that we want to search:

import os

cwd = os.getcwd()
desktop = os.path.join(cwd, "Desktop")

This code generates the file path for the Desktop folder relative to our current working directory. Next, we can use the Python os.listdir() method to retrieve a list of all the files in this folder:

files = os.listdir(desktop)

This method returns a list of the names of all files that appear in the Desktop folder. It does not include the paths of the files. Now that we have this list of files, we can print them all to the console. We’re going to print the full file path for each file using os.path.join and a Python for loop:

for f in files:
	print(os.path.join(desktop, f))

This code loops through all the files in the Desktop folder. It merges the name of each file with the path name of the Desktop folder. Our code returns:

/Users/James/Desktop/.DS_Store
/Users/James/Desktop/Notes.md
/Users/James/Desktop/To-dos.md

There are three files on my desktop: .DS_Store, Notes.md, and To-dos.md. We used os.path.join() to generate the full paths of each file.

Conclusion

The os.path.join method combines components in a path name to create a full path name.

This method makes it easy to combine two or more components of a path name. Os.path.join automatically inserts forward slashes (“/”) into the path name when needed.

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If you want to learn more about the Python programming language, check out our How to Learn Python guide.