Capture output while handling a failed command.
Bash Scripts: An assignment inherits the status of its command substitution, allowing both output and status to be handled.
set -euo pipefail
if output=$(bash -c 'printf "partial\n"; exit 3'); then
status=0
else
status=$?
fi
printf "%s:%s\n" "$status" "$output"Expected output EXAMPLE
3:partial
Details
Requires Bash 4 or later. Save as snippet.sh and run bash snippet.sh in an empty working directory. An assignment inherits the status of its command substitution, allowing both output and status to be handled.
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
51cffedc495271f0e4cdda3b4095d7863afcb9e71bf179f9bbbe3d61e6b1b130- 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
3:partial
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.