A searchable quick reference for systemctl and journalctl — controlling services, inspecting units, and reading logs.
Nginx Cheatsheet
A searchable quick reference for nginx — CLI, server and location matching, proxy_pass, headers, TLS, redirects, rewrites, gzip, rate limiting, upstreams, and variables.
TCP/UDP Ports Cheatsheet
A searchable quick reference for well-known and commonly-used TCP/UDP ports — web, mail, infra, databases, and dev servers.