I work on data center infrastructure. When something breaks at 2 a.m., nobody re-reads a 400-page manual — you reach for the handful of commands you half-remember and hope you get the flags right.

So I started writing one-page cheatsheets for the commands I keep looking up, and publishing them as open source. The first set covered everyday tools (git, docker, curl, jq, regex). This one is the infrastructure set: SSH, systemd, and kubectl — the three I actually keep open during incidents.

Every command below is copied verbatim from the cheatsheets, and every flag in them was checked against the real tools (OpenSSH 9.6 man pages, systemd 255, the official kubectl reference).

SSH: tunnels and jump hosts, not just login

Most people use SSH to log in.…