Create a file without overwriting an existing one.
Python: Use exclusive creation mode and handle FileExistsError explicitly.
from pathlib import Path
try:
with open("notes.txt", "x", encoding="utf-8") as file:
file.write("new")
except FileExistsError:
print("Already exists")
print(Path("notes.txt").read_text(encoding="utf-8"))Expected output EXAMPLE
Already exists original
Details
Save as snippet.py and run python3 snippet.py. Uses the Python standard library. Use exclusive creation mode and handle FileExistsError explicitly.
Tested on Ubuntu 24.04.5 LTS · · Python 3.12.3 · python3 3.12.3-0ubuntu2.1
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
python3 -c <published code>- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
49ca7f163ed545258842948e71a8dc7514398f8faa70997b9fc34b537da03504- Dependencies
- python3 3.12.3-0ubuntu2.1
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
printf 'original' > notes.txt
Observed standard output
Already exists original
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.
Additional assertions that passed
Checks recorded by the test harness. Where Python assertions are shown, browser cases use Playwright and simulator cases may inspect pin transitions: result.stdout is captured output, work is the temporary directory, and Path is pathlib.Path. The harness also imports json and csv.
assert Path('notes.txt').read_text() == 'original'