Missing: When using "set -o pipefail" you should also catch any non-zero return codes that you want to accept, e.g., "{ grep -o pattern file || true ; } | sed p

Missing: When using "set -o pipefail" you should also catch any non-zero return codes that you want to accept, e.g., "{ grep -o pattern file || true ; } | sed pattern" to let the command continue (if desired) to execute even if pattern isn't found.