Print only duplicate values.
Linux Commands: Use uniq -d after sorting to report each repeated value once.
printf 'a\nb\na\nc\nc\n' | LC_ALL=C sort | uniq -dExpected output EXAMPLE
a c
Details
Run in Bash on GNU/Linux in a scratch directory. Tested with the GNU utilities supplied by Ubuntu. Use uniq -d after sorting to report each repeated value once.
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; sed 4.9-2ubuntu0.24.04.1
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
bash -euo pipefail -c <published code>- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
26b4a45b5101fd8303e5d43469fc9a43a43f01a82cc2aec56cb9c4dcc6953dd4- Dependencies
- bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; sed 4.9-2ubuntu0.24.04.1
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.
# No input files required.
Observed standard output
a c
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.