Replace a text file with an atomic rename.
Prepare new content beside the target before renaming it into place.
set -euo pipefail
temp_file=$(mktemp ./settings.XXXXXX)
trap 'rm -f -- "$temp_file"' EXIT
printf "mode=production\n" > "$temp_file"
mv -- "$temp_file" settings.txt
cat settings.txtExpected output EXAMPLE
mode=production
Details
Requires Bash 4 or later. Save as snippet.sh and run bash snippet.sh in an empty working directory. Creating the temporary file in the same directory keeps the rename on one filesystem. This does not guarantee durability after a power failure.
Tested on Ubuntu 24.04.5 LTS · · GNU bash, version 5.2.21(1)-release (x86_64-pc-linux-gnu) · bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Snippet process uid 65534 with a read-only root filesystem and temporary working files. Networking disabled. 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 process) / C.UTF-8
- Interpreter invocation
bash -euo pipefail -c <published code>- Container image ID
sha256:ec91410a8f6ec3e985830b5e3a0560306d36f8c1c5ccd91a6699abe707123fa3- Code SHA-256
7800bb996201d57a425098669fbf168bdf4295408f3c0d8cd4c9d1d7e017600e- Dependencies
- bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3
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.
# No input files required.
Observed standard output
mode=production
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('settings.txt').read_text() == 'mode=production\n'