temporary-files.md

Python by Example: Temporary Files

Temporary files and directories are useful for testing, caching, or intermediate data. The tempfile module creates them with unique names and lets you control cleanup. NamedTemporaryFile gives a file; TemporaryDirectory gives a directory that is removed when the context exits. Use delete=False if you need the file to persist after the context.

What you'll learn:

• NamedTemporaryFile for temp files
• TemporaryDirectory for temp directories
• When to use delete=False

import tempfile
import os

# Named temporary file
with tempfile.NamedTemporaryFile(mode="w", suffix=".txt", delete=False) as f:
    f.write("temporary content")
    path = f.name

print(path)
with open(path) as f:
    print(f.read())
os.unlink(path)

# Temporary directory
with tempfile.TemporaryDirectory() as tmpdir:
    filepath = os.path.join(tmpdir, "test.txt")
    with open(filepath, "w") as f:
        f.write("hello")
    print(os.path.exists(filepath))
print("Directory removed")

With default delete=True, the temp file is removed when the with block exits. We use delete=False so we can read it after. TemporaryDirectory always removes the directory when the block exits.

To run this program:

$ python source/temporary-files.py
/tmp/tmp...               # path varies each run
temporary content
True
Directory removed

Tip: Don't use tempfile.mktemp()—it has a race condition. Use NamedTemporaryFile or mkstemp instead.

Try it: Create a temp directory, write a file in it, read it back, then let the context manager clean up.

Source: temporary-files.py

Next: Command-Line Arguments