The Alert Never Fired Because the Loop Skipped the Last Line of the File (opens in new tab)

We kept a plaintext file of hostnames, one per line, and a monitoring script read the file and pinged each host every five minutes. When a host failed to respond, the script sent an email alert. The system had been running for months and it worked — we had caught three actual outages with it, which gave us real confidence in the setup. app-07 was added to the list on a Thursday afternoon. The engineer who added it was using VS Code on a Mac, and VS Code by default does not add a trailing newl...