SysAdmin

A quick way to inspect what SELECT and UPDATE privileges a MySQL user actually holds, straight from the mysql.user table. Useful when an application is throwing permission errors and you need to confirm what the account can and cannot do.

A quick walkthrough of using virt-rescue to generate the correct mount commands for a chroot rescue session on a libvirt guest.

Two quick one-liners that count how many unique remote IPs are connected to port 80, using either netstat or ss. Handy for spotting unexpected traffic or verifying that only expected clients are hitting your web server.

Generate a fresh rndc.key and wire it into rndc.conf so your BIND name server accepts authenticated remote control commands. Covers the rndc-confgen command and the full rndc.conf structure.

Learn how to extract dynamic symbols from the mysqld binary and use them to resolve a crash stack dump into readable function names.

Find where cron logs live on your Linux system and learn how to read them to confirm scheduled jobs actually ran.