Handle an expected command failure.

Branch on a command’s exit code without aborting the script.

set -euo pipefail
if grep -q "missing" notes.txt; then
  printf "Found\n"
else
  printf "Not found\n"
fi

Expected output EXAMPLE

Not found

Details

Requires Bash 4 or later. Save as snippet.sh and run bash snippet.sh in an empty working directory. Commands used as an if condition may fail without triggering set -e.

✓ Verified

Tested on Ubuntu 24.04.5 LTS · 2026-11-02 18:21:08 UTC · 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: 4b8cec700c67eadeed641abd6b2672d1e2c540898972cff792d676f47b187d5a
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.

printf 'hello\n' > notes.txt

Observed standard output

Not found

Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.