SysAdmin

A practical breakdown of how Linux file permissions work, including the symbolic and numeric chmod methods, special bits like setuid and sticky, and how permissions differ between files and directories.

A practical guide to reading Linux load averages, with a traffic analogy that makes the numbers click. Learn the thresholds that matter, how multi-core systems change the math, and which of the three averages to watch.

A quick bash one-liner that lists every disk label present in /dev/disk/by-label/ that is not currently mounted, so you can spot forgotten or orphaned volumes at a glance.

Tune Linux VM memory behavior by adjusting vfs_cache_pressure, dirty_ratio, and swappiness to reduce unnecessary swapping and improve I/O throughput.

Use Apache mod_rewrite to return a 400 error for a specific URI and optionally block hotlinking from other domains. A quick .htaccess snippet that keeps unwanted traffic off a single page.

LDAP error 53 means the destination server is refusing a password change request. This post walks through the most common Active Directory requirements and policy settings that trigger the error.