Bash

A deep dive into why MySQL on NUMA systems suffers from unpredictable swapping, and how a single numactl interleave fix eliminates the problem entirely.

A follow-up to the original MySQL NUMA swap post, explaining why the real issue is memory pressure on a single NUMA node rather than swap itself, and outlining a three-part solution for balanced allocation in production.

A quick reference for backing up and restoring full ACL permissions across an entire directory tree using getfacl and setfacl.

A quick reference for the process state codes shown in the STAT column of ps aux, including both standard and BSD-specific flags.

A practical cheat sheet covering common regex patterns, Perl-compatible lookarounds, and character classes for everyday text processing in bash and grep.

A quick iptables one-liner to reject TCP traffic from a specific source IP with a TCP reset, tagged with a human-readable comment for future reference.