Remove a variable from one child’s environment.
Bash Scripts: env -u removes an inherited value for a single command.
set -euo pipefail
export TASK_MODE=ready
env -u TASK_MODE bash -c 'printf "%s\n" "${TASK_MODE:-missing}"'
printf "%s\n" "$TASK_MODE"Expected output EXAMPLE
missing ready
Details
Requires Bash 4 or later. Save as snippet.sh and run bash snippet.sh in an empty working directory. env -u removes an inherited value for a single command.
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
3b058c51a9959417eb3d06e6b75b99f452969509c0f576a370526cd3cc2ec26f- 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
missing ready
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.