Piping a command's output to tail silently hides its real exit status

A developer discovered on September 4, 2026, that running a Node.js script through a pipe to tail caused the shell to report exit code 0, even though the script had actually failed with exit code 1. This happens because in bash, the $? variable after a pipeline reflects the exit status of the last command in the pipe — in this case, tail — not the original program. The issue was especially problematic in a control run, where accurately capturing failure is critical, since a masked exit code made a genuinely failed check appear successful. The developer recommends either running the command on its own line, using bash's PIPESTATUS[0] array immediately after the pipeline, or enabling set -o pipefail in scripts, each with its own caveats. The bug was found by accident rather than deliberate auditing, and the author acknowledges similar issues may exist elsewhere in their codebase.