Susumu Takahashi

6 min read

Susumu Takahashi

Oct 30

PHP, WordPress core, plugins, themes — who updates what? Splitting "the host's job" from "the site owner's job" on shared hosting

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 29

Database Index Basics — Why the Same WHERE Clause Can Use an Index or Scan Every Row

#python #webdev #programming

5 min read

Susumu Takahashi

Oct 28

Why Meta Descriptions Have a Length Limit — and the HTML Entity Trap That Inflates the Count

#wordpress #php #tutorial

5 min read

Susumu Takahashi

Oct 27

robots.txt and sitemap.xml Basics — What They Tell Crawlers, and Which One Wins

#wordpress #php #tutorial

5 min read

Susumu Takahashi

Oct 26

gzip/Brotli Compression Basics — How HTTP Responses Get Smaller, and Why the Server Gets to Choose

#python #webdev #programming

5 min read

Susumu Takahashi

Oct 24

OGP (Open Graph Protocol) Basics — How Social Media Decides What a Shared Link Looks Like

#wordpress #php #tutorial

5 min read

Susumu Takahashi

Oct 23

JSON-LD Structured Data Basics — How Rich Results Get Generated

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 22

hreflang Basics — How Search Engines Recognize a JP/EN Article Pair

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 21

The Basics of esc_html() and esc_attr() — WordPress's "Escape on Output" Approach to XSS

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 19

The Basics of `$wpdb->prepare()` — Why You Should Never Build SQL Queries With String Concatenation

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 19

WordPress Hooks Explained: How Plugins and Themes Extend Core Without Editing It

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 17

Timezone Conversion Pitfalls: Where UTC/JST Bugs Actually Come From

#python #webdev #programming

5 min read

Susumu Takahashi

Oct 16

Optimistic vs. Pessimistic Locking: Two Ways to Stop Database Updates From Colliding

#python #webdev #programming

5 min read

Susumu Takahashi

Oct 15

Git Bisect and Blame: Binary-Searching Your Way to "When Did This Break?"

#python #webdev #programming

4 min read

Susumu Takahashi

Oct 14

JWT and Session Tokens Explained: Stateless vs. Stateful Authentication

#python #webdev #programming

4 min read

Susumu Takahashi

Oct 13

CORS Explained: Why Browsers Block Cross-Origin API Requests

#python #webdev #programming

4 min read

Susumu Takahashi

Oct 8

Environment Variables and .env Files: What Wins When They Conflict?

#python #webdev #programming

4

3 min read

Susumu Takahashi

Oct 8

How Python's venv Works — Why It Keeps Projects From Fighting Over the System Python

#python #webdev #programming

4 min read

Susumu Takahashi

Oct 6

Image Optimization and WebP Basics — Why WebP Is Smaller, and How Browsers Decide to Use It

#wordpress #php #tutorial

5 min read

Susumu Takahashi

Oct 6

Cookie and Session Authentication Basics — What Happens Behind a wp-admin Login

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 5

REST API Authentication: Cookie+Nonce vs. Application Passwords

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Oct 3

Queues and Thread Pools — Why Submission Order and Completion Order Aren't the Same

#python #webdev #programming

4 min read

Susumu Takahashi

Oct 2

Git's Staging Area — What Actually Happens Between `git add` and `git commit`

#python #webdev #programming

4 min read

Susumu Takahashi

Oct 1

TLS Certificate Verification — What "Chain of Trust" Actually Means

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 30

DNS Records Explained — What A, CNAME, and TXT Records Actually Point To

#wordpress #php #tutorial

4

4 min read

Susumu Takahashi

Sep 29

pip Version Specifiers — What `==`, `>=`, and `~=` Actually Commit You To

#python #webdev #programming

4 min read

Susumu Takahashi

Sep 27

Cache-Control vs. ETag: What Each One Actually Controls

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 26

Exponential Backoff vs. Fixed-Interval Retries: When Growing Wait Times Actually Help

#python #webdev #programming

4

5 min read

Susumu Takahashi

Sep 24

Why SSH Key Authentication Beats Password Authentication — What Is Actually Being Proven

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 24

Unit Tests vs. Regression Tests: Why the Same Feature Gets Tested Twice

#python #webdev #programming

5 min read

Susumu Takahashi

Sep 22

How Desktop Apps Detect and Kill Stale Processes on Startup

#python #webdev #programming

5 min read

Susumu Takahashi

Sep 20

Semantic Versioning (SemVer): Why Version Numbers Have Three Parts

#python #webdev #programming

4 min read

Susumu Takahashi

Sep 19

How Symmetric Encryption (Fernet) Keeps Local Credentials Safe on Disk

#python #webdev #programming

5 min read

Susumu Takahashi

Sep 18

What `rsync -avz --delete` Actually Does

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 17

HTTP Status Code Basics: What 200/301/403/500 Actually Mean for Maintenance Tools

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 16

Reading `.htaccess` mod_rewrite Rules: A Real `RewriteBase` Trap From a Subdomain Migration

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 15

wp-config.php Key Constants Explained: What WP_DEBUG, DISALLOW_FILE_EDIT, and WP_MEMORY_LIMIT Actually Do

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 14

WordPress REST API Basics: What Can You Do With `/wp-json/`?

#wordpress #php #tutorial

5 min read

Susumu Takahashi

Sep 12

What Is Visual Regression Testing? How Screenshot Diffing Catches Layout Breaks

#python #webdev #programming

5 min read

Susumu Takahashi

Sep 11

What are PyInstaller "hidden imports" — and why do only dynamic imports break?

#python #webdev #programming

4 min read

Susumu Takahashi

Sep 9

Code signing basics — what Apple Notarization and Windows Authenticode actually certify

#python #webdev #programming

4 min read

Susumu Takahashi

Sep 9

Running Flask's dev server as a desktop app's backend — what actually matters

#python #webdev #programming

6 min read

Susumu Takahashi

Sep 8

Atomic writes — how tempfile + os.replace prevent corrupted JSON

#python #webdev #programming

5 min read

Susumu Takahashi

Sep 7

Cross-platform file locking in Python — fcntl vs msvcrt from scratch

#python #webdev #programming

5 min read

Susumu Takahashi

Sep 5

Crontab syntax basics, and how it differs from WP-Cron

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 4

Organizing per-host settings with `~/.ssh/config` — a standard practice for anyone managing multiple servers

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 3

SSH key types (RSA / ED25519 / ECDSA) — what actually differs, and which one to pick

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 2

How the WordPress transient API works, and when `wp transient delete` actually helps

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Sep 1

`wp db check` / `wp db optimize` — the database health commands that get overlooked

#wordpress #php #tutorial

3 min read

Susumu Takahashi

Aug 31

Using WP-CLI aliases to switch between multiple WordPress environments safely

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Aug 28

Comparing pricing models across four WordPress maintenance tools — what the shape of a price reveals about cost structure

#wordpress #php #tutorial

4 min read

Susumu Takahashi

Aug 28

A tabbed form that silently refused to submit — required fields hidden behind another tab

#python #webdev #programming

8

10

4 min read

Susumu Takahashi

Aug 27

UTF-8 vs. cp932: Why Some Bugs Only Show Up on Japanese Windows

#python #webdev #programming

4 min read

Susumu Takahashi

Aug 25

Verifying a WordPress major upgrade — a 7-step post-upgrade checklist

#wordpress #php #tutorial

6 min read

Susumu Takahashi

Aug 24

Greedy vs. Non-Greedy Regex: Why the Same Pattern Can Match Differently

#python #webdev #programming

5 min read

Susumu Takahashi

Aug 23

Log Level Design and Rotation: Why Apps Use DEBUG/INFO/WARNING/ERROR

#python #webdev #programming

5 min read

Susumu Takahashi

Aug 22

Site list scrolls to top on every delete — fixing the missing keepScroll argument across 6 call sites

#python #webdev #programming

2 min read

Susumu Takahashi

Aug 21

The Principle of Least Privilege: Why File Permissions Like 600/644/755 Exist

#python #webdev #programming