sha256sum --check: how to verify backup integrity
Reproducible SHA-256 manifest verification: successful match, single-byte alteration, missing file, strict mode, and boundaries — why a matching hash does not prove recoverability.
Михаил
5 minViews4
GENERAL IT · JOURNAL
Technology in practice
Ideas, experience and solutions for your project.
application/problem+json: How Not to Mistake an HTML Error for JSON
A practical guide to RFC 9457: first check the HTTP status and Content-Type, then safely parse Problem Details. Using Python 3.12, we reproduce a correct 422 response, HTML from a gateway, broken JSON, incorrect types, and status mismatches.
Денис
8 minViews9
Catalog Acceptance After Import: How Many Cards to Check and How Long It Takes
A training model helps assemble a risk-oriented sample after catalog import, calculate labor effort, and determine when a single found error requires searching the entire product group.
Вера
8 minViews3
rsync --dry-run: How to See Deletions and Overwrites Before Synchronization
A practical guide to safely checking rsync: read the itemized output, spot deleted files, and detect content changes when size and timestamp are identical.
Михаил
6 minViews4
ETag and If-Match: How to Avoid Overwriting Stock During Dual API Updates
A practical guide to protecting APIs from stale records: two clients read the same product, the first updates the stock, the second receives a 412 and retries the update only after a new GET.
Денис
11 minViews5
How much does an hour of checkout downtime cost a store
A training model helps estimate the direct cost of a checkout failure, account for recovered purchases, and determine when it makes sense to pay for faster response.
Вера
6 minViews4
Permission denied: How to find a directory without search permission using namei
Practical diagnosis of Permission denied in Linux: decompose the path with namei -l, locate an intermediate directory lacking search permission x, and verify a targeted fix without recursive chmod.
Михаил
6 minViews5
429 Retry-After: Seconds or Date — Checking the API Client's Wait Time
Practical analysis of two Retry-After formats for HTTP 429: parsing seconds and HTTP dates, limiting wait time, and testing six boundary cases in Python 3.12.
Денис
5 minViews4
A repeated webhook must not create a second order: testing idempotency
A practical analysis of a webhook receiver: a stable event_id, a UNIQUE constraint, a transaction, a retry after a failure, and two simultaneous deliveries. The tutorial example was implemented and verified on Python 3.12 and SQLite 3.53.
Денис
10 minViews7
How to Verify fstab Before Reboot: findmnt Without mount -a
We verify the candidate fstab using findmnt --verify, analyze return codes and method limitations without mounting disks or altering the active configuration.
Михаил
6 minViews9
Free Shipping: What Threshold Won't Eat the Store's Margin
A teaching model helps calculate the free shipping threshold based on cart margin, variable costs, and subsidies, then test the rule against real orders.
Вера
5 minViews7
Average Position in Search Console Changed: How to Understand What Happened
I analyze Google's average position by individual impressions and demonstrate via a sample calculation how device composition can shift the overall metric without movement within segments.
Альбина
5 minViews8
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