https://vixyun.top/posts/ Short notes on productivity, tools and technology. Hugo en Mon, 19 Oct 2026 10:30:00 +0800 https://vixyun.top/posts/qr-code-size-version-and-level/ Mon, 19 Oct 2026 10:30:00 +0800 https://vixyun.top/posts/qr-code-size-version-and-level/ A QR version is a size, not a quality: what your text costs in bits, which level pushes it into a bigger grid, and how many millimetres that needs on paper. https://vixyun.top/posts/502-bad-gateway-troubleshooting/ Sun, 04 Oct 2026 11:40:00 +0800 https://vixyun.top/posts/502-bad-gateway-troubleshooting/ Measured in a browser: a 502 with a body shows the server's own page, an empty 502 shows nothing, and a killed connection produces no number at all. https://vixyun.top/posts/cron-expression-how-to-read/ Sun, 04 Oct 2026 11:20:00 +0800 https://vixyun.top/posts/cron-expression-how-to-read/ Why */5 aligns to midnight, not to your last run, the day-or-weekday union rule (0 0 13 * 5 runs 62 times a year), the 29 Feb wait, DST, and a checklist. https://vixyun.top/posts/password-entropy-crack-time/ Sun, 04 Oct 2026 11:00:00 +0800 https://vixyun.top/posts/password-entropy-crack-time/ Bits come only from how a password was sampled: length × log2(pool). Crack times for 8-to-20-character passwords at three attack rates, and what entropy misses. https://vixyun.top/posts/verify-downloaded-file-checksum/ Sun, 04 Oct 2026 10:40:00 +0800 https://vixyun.top/posts/verify-downloaded-file-checksum/ sha256sum, Get-FileHash, certutil and shasum compared, the order to debug a mismatched digest, what MD5 and SHA-1 are still good for, why CRC32 is not a hash. https://vixyun.top/posts/url-encoding-plus-vs-percent20/ Sun, 04 Oct 2026 10:20:00 +0800 https://vixyun.top/posts/url-encoding-plus-vs-percent20/ Spaces have three legal spellings, + is a space only in a query, ; is not a parameter separator, and a lone percent throws URIError. Work segment by segment. https://vixyun.top/posts/base64-encoding-chinese/ Sun, 04 Oct 2026 10:00:00 +0800 https://vixyun.top/posts/base64-encoding-chinese/ btoa('你好') throws and atob returns mojibake because Base64 works on bytes, not characters. The UTF-8 round trip, padding, why + breaks tokens, base64url. https://vixyun.top/posts/csv-to-json-conversion-pitfalls/ Sun, 04 Oct 2026 09:40:00 +0800 https://vixyun.top/posts/csv-to-json-conversion-pitfalls/ Why 007 became 7, why splitting on a comma shreds rows, why European spreadsheets export semicolon CSV, and what to do with ragged rows and duplicate headers. https://vixyun.top/posts/working-days-and-deadline-counting/ Sun, 04 Oct 2026 09:20:00 +0800 https://vixyun.top/posts/working-days-and-deadline-counting/ One pair of dates has four right answers: calendar days, whole weeks, working days, years-months-days. Covers endpoint rules, month-end clamping and due dates. https://vixyun.top/posts/unix-timestamp-to-beijing-time/ Sun, 04 Oct 2026 09:00:00 +0800 https://vixyun.top/posts/unix-timestamp-to-beijing-time/ A Unix timestamp carries no timezone: Beijing time is the same instant at UTC+8. Ten versus thirteen digits, the 8-hour bug, and the 1986-1991 DST years. https://vixyun.top/posts/hello-vixyun/ Tue, 17 Feb 2026 00:00:00 +0800 https://vixyun.top/posts/hello-vixyun/ The site is live. A quick note on what it is, how it's built, and what's next.