Practical notes for developers and system engineers
Learn why identical-looking Unicode strings compare differently, how NFC and NFKC change them, and how to preserve names while creating search keys.
Trace supplementary Unicode characters through input, transport, storage and fonts, with UTF-16 examples and MySQL utf8mb4 checks.
Resolve CharacterStringTooLong by keeping quoted DKIM chunks in one Route 53 TXT value, rather than creating separate values on new lines.
Update an existing Git clone to a moved repository, check fetch and push URLs, and verify access without recloning.
Find the SSH executable and client config file, inspect Host matches, and diagnose setting order and command-line overrides with ssh -G.
Check SSH or HTTPS TCP connectivity on Windows and distinguish network reachability from DNS, authentication and certificate failures.
Query A and AAAA records, inspect configured DNS servers, and compare a specific resolver without changing Windows DNS settings.
Compare UTF-16 code units, Unicode code points and grapheme clusters. Count and shorten names and emoji without breaking them.