Bash
str_replace() in Bash: Replace Text in a String
Replace text in a Bash string without sed: ${s//search/replace}, anchored replacements, why you must quote the search, and what Bash 5.2 did to &.
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Linux
rsync Recipes: Trailing Slashes, --delete and Filters
One missing slash nests a directory. One empty source wipes a backup. Tested rsync recipes for mirroring, filtering, verifying and copying over SSH.
Bash
trim() in Bash: Strip Leading and Trailing Whitespace
PHP-style trim(), ltrim() and rtrim() in pure Bash with parameter expansion, plus why the popular read trick quietly removes your backslashes.
Web
How nginx Chooses a location Block: Prefixes, Regexes and ^~
Not first match, not longest match, but a mix of both. A test config where every location names itself shows exactly how nginx picks one, and where it surprises.
Programming
Python subprocess.run() Instead of os.system()
Why I convert os.system() calls to subprocess.run(): no shell injection, real exit codes, captured output, timeouts and input, with notes for Python 3.6.
Web
nginx try_files Explained: Static Sites and PHP Front Controllers
try_files checks files in order and only the last argument redirects. Static clean URLs, a PHP front controller with php-fpm, and the upload exploit it prevents.
Linux
Docker Volumes vs Bind Mounts, and the File Ownership Trap
Why a volume shows the image's files and a bind mount hides them, and how a root container leaves files your own user cannot edit or delete. Four tested fixes.
Linux
systemd Timers: A Practical Replacement for Cron Jobs
Cron loses output, overlaps jobs and skips runs while the machine is off. systemd timers fix all three. A tested walk-through with OnCalendar examples.
Linux
Docker Multi-Stage Builds: Smaller Images, Same Result
The same 147 kB binary in a 257 MB image or an 8.44 MB one. Multi-stage builds, named stages, a --target debug image, and why build secrets still leak.
Programming
PHP 8 Nullsafe Operator ?-> vs ?? and isset()
?->, ?? and ??= all deal with null, but they solve different problems. Tested examples of each, short-circuiting, and the places where ?-> is not allowed.