Practitioner reference for Elasticsearch 9.x: index and document operations, Query DSL, aggregations, vector / kNN search, ESQL, cluster management, version compatibility notes, and the gotchas that bite first-time operators.
MySQL cheat sheet covering CLI commands, database and table operations, joins, indexes, backups, user management, and transactions, with version notes for 5.7, 8.0, and 8.4.
Regex Cheat Sheet including regex symbols, ranges, grouping, assertions, syntax tables, examples, matches, and compatibility tables. Definitive Regular Expressions Quick Reference!
A scannable curl reference: GET, POST, PUT, DELETE; JSON and form bodies; basic, bearer, and digest auth; redirects, retries, timeouts; --resolve overrides, SOCKS proxies; with PowerShell Invoke-WebRequest equivalents.
A scannable SSH reference: ssh-keygen, ssh-copy-id, port forwarding (-L, -R, -D), ProxyJump, ~/.ssh/config blocks, scp and rsync over SSH, with the Windows OpenSSH differences and PuTTY equivalents.
A scannable find reference: search by name, size, time, type, perms; safe pipelines with -print0 and xargs -0; -exec and -execdir; plus the macOS BSD vs GNU find divergences and Windows PowerShell equivalents.
A scannable grep reference with the flags I actually use, the GNU vs BSD differences that bite on macOS, and the Windows equivalents (Select-String, findstr) for the same patterns.
A scannable AWS S3 CLI reference: aws s3 cp, sync, mv, rm, ls; recursive uploads and downloads; --exclude / --include filters; storage classes (STANDARD_IA, GLACIER, INTELLIGENT_TIERING); SSE encryption (AES256, aws:kms); --dryrun safety; the trailing-slash gotcha; concurrency tuning via max_concurrent_requests and multipart_chunksize; cross-account profiles.
Every torrc directive worth knowing in 2026, grouped by what you're trying to do: SOCKS and control ports, circuit construction, country pinning, hidden services, bridges, logging, and performance tuning.