Python Basics: Creating Temporary Files with tempfile

Python’s standard-library tempfile module creates temporary files and directories for tests and intermediate results.

Use Python 3.12 or newer on Linux. Each example creates a fresh disposable directory. Warning: leaving a TemporaryDirectory context removes that directory and everything inside it. Keep anything you need elsewhere before the block ends.

Work inside a temporary directory

Save as demo_tempfile_1.py:

from pathlib import Path
from tempfile import TemporaryDirectory

with TemporaryDirectory() as temporary_directory:
    workspace = Path(temporary_directory)
    report_path = workspace / "report.txt"
    with report_path.open("x", encoding="utf-8") as report_file:
        report_file.write("Processed 3 records\n")

    print(report_path.read_text(encoding="utf-8"), end="")
    print("Inside context:", workspace.exists())

print("After context:", workspace.exists())

Run:

python3 demo_tempfile_1.py

Output:

Processed 3 records
Inside context: True
After context: False

TemporaryDirectory() supplies a unique directory name. Printing its state instead of its generated path keeps output predictable. Mode "x" creates a file exclusively and raises FileExistsError instead of overwriting an existing file.

Read back a temporary text file

NamedTemporaryFile() provides an open file with a filesystem name. With its default deletion settings, closing it removes the file. The outer context removes the directory.

Save as demo_tempfile_2.py:

from pathlib import Path
from tempfile import NamedTemporaryFile, TemporaryDirectory

with TemporaryDirectory() as temporary_directory:
    with NamedTemporaryFile(
        mode="w+t", encoding="utf-8", suffix=".txt",
        dir=temporary_directory,
    ) as temporary_file:
        temporary_path = Path(temporary_file.name)
        temporary_file.write("Ready for import\n")
        temporary_file.seek(0)
        print(temporary_file.read(), end="")
        print("File exists:", temporary_path.exists())

    print("After close:", temporary_path.exists())

Run:

python3 demo_tempfile_2.py

Output:

Ready for import
File exists: True
After close: False

The default mode is binary ("w+b"). Here "w+t" accepts text, and + permits reading and writing. After writing, the cursor is at the end; seek(0) moves it back before reading.

Cleanup also runs when a normal Python exception leaves the block. Abrupt process termination can leave files behind. Temporary paths are unsuitable for lasting results.

References

• Python tempfile documentation
• Python file input and output tutorial

Acknowledgements

This post was created with assistance from AI.