Open() in Python does not create a file if it doesn't exist

python

file-io

context-managers

error-handling

byAlex Kataev·Jan 7, 2025

To make Python create a nonexistent file during an open() operation, use either the 'w+' or 'a+' mode:

with open('yet_another_file.txt', 'w+'): pass  # Creates or truncates the file
with open('yet_another_file.txt', 'a+'): pass  # Creates or preserves the file's content

In this snippet, 'w+' stands for write plus rewrite history, and 'a+' stands for append plus remember the past. Translation: 'w+' truncates existing content or creates a new file, and 'a+' preserves existing content or creates a new file. No file? No problem!

Breaking down the file modes

Understandably, file modes in Python resemble an encrypted alphabet than an intuitive coding feature. But once you decipher them, they're quite simple!

The 'w+' mode tells Python, "Hey, I want to overwrite my diary. Make it, if it doesn't exist. And oh, I want to read it sometimes." Python nods and follows your order like a loyal knight.

Whereas 'a+' mode says, "Listen, Python. I want to add more to my diary, but keep the memories intact. Make the diary if it's not there. And reading my old notes? Yup, I'll do that too." Python gets it and acts accordingly, keeping all of your precious memories safe. But remember, Python initially stays at the end of those 'memories', so remind it to rewind.

# An innocent, naive Python would do this.
f.seek(0)  # "Python, reviewing time! Back to the memory lane."

Maybe you're someone who uses modes like 'r+', a shy mode that doesn't dare to create a file but can read and write if it exists. Check your file's existence first, then play safe.

# Being Sherlock before messing files.
if not os.path.exists(file_path):
    mode = 'w+'
else:
    mode = 'r+'
with open(file_path, mode) as f:
    f.write('Masterpiece Python code')

Sometimes, the real world interferes with your perfect Python world. The bouncer named directory permissions can deny your file-making entry. So make sure your Linux permissions stand at 775 (or similar) — like a secret club entry code.

Your file I/O survival toolkit

Give your file operations an upgrade with these I/O survival tools:

Context managers: Your cleanup crew

Think of context managers as an efficient cleanup crew, ensuring your resources are gathered and disbanded correctly. The result: no more feared resource leaks.

with open('story_of_my_life.txt', 'w+') as f:
    f.write('I once wrote a Python script...')
# The cleanup crew closes the file here, while you sip on your coffee.

Error handling: The safety net

All great acrobats use a safety net: wrap your file operations in a try-except block to catch those unexpected falls, whether they're permissions issues, phantom directories, or capricious disks.

try:
    with open('secrets_of_universe.txt', 'w+') as f:
        f.write('42...')
except IOError as e:
    print(f"Oops, universe said {e}")

pathlib: The modern file artist

Thinking about creating directories? The pathlib module from Python 3.4+ is your modern sculptor, crafting directories with style:

from pathlib import Path

# Crafting beautiful file art:
Path('masterpiece.txt').touch()

# Or building entire directory sculptures:
Path('art_gallery').mkdir(parents=True, exist_ok=True)