Guides
Task-focused articles: how to use the tools for real jobs, with worked examples and limits.
Shrink a PDF so it fits an email attachment limitA scanned 28 MB document will not send. Here is how to get it under the limit, and what to do when compression is not enough.Put two screenshots side by side for a bug reportExpected vs actual, before vs after — one combined image is easier to review than two attachments. Here is the fast way to make one.Share your Wi-Fi with a QR code instead of spelling the passwordA QR code on the wall ends the “capital M, lowercase k, two sevens” ritual. How the format works, what to check, and when not to print one.Turn a column of values into a comma-separated listSpreadsheet column to IN(...) list, tags to a line, IDs to a query. The two-minute conversion that keeps coming back.chmod 755 vs 644: which permissions for files, folders, and scriptsThe two numbers cover most of what a web server needs. What each digit means, which to pick, and the cases where neither is right.Cron expressions explained with schedules you actually useFive fields, a few operators, and one famous trap. Work through real expressions — backups, business-hours checks, monthly jobs — and check the next run times.Encrypt a note before pasting it into chat or emailRecovery codes, API keys, door PINs — some text should not sit in a chat log in the clear. How to encrypt it here, and what this does and does not protect.Convert wareki years on Japanese forms without a lookup table平成5年 is which Gregorian year? Forms for resumes, applications, and registrations still ask in wareki. Boundary years trip everyone up — here is how to get them right.