Tag: linux

A kernel upgrade halved one team's PostgreSQL throughput. The fix was kernel tuning: huge pages, THP, swappiness, I/O scheduler. Here's what matters and why.

Run multiple Proxmox VMs and LXC containers behind a single public IP using NAT bridging and iptables port forwarding. Works on Proxmox VE 8 and 9.

Attackers love finding ways to go from www-data to root. Here's how they do it, and more importantly, how you harden your Linux boxes to stop them.

Out of RAM and no time to reimage? Add swap via a file on any partition using mkswap, swapon, and fstab, done in under 5 minutes.

Master bash for loops, while loops, and seq for sequential counting, iterate over files, ranges, and arrays without losing your mind.

Count files in a directory (recursively or not) with find, ls, and tree, quick one-liners for when du just isn't telling you enough.

Your disk is full and du is lying to you. ncdu, df, and find tricks to track down space hogs before your server goes down at 2 AM.

Extract tar.gz, tar.bz2, tar.xz, flags demystified, compression compared, directory extraction, and the gotchas that trip you up.

Use su with a specific shell to switch users without the default login shell, useful when /etc/passwd points to something unexpected.

logrotate keeps your /var/log from eating the disk, configure rotation schedules, compression, and retention for any service log.

Master MySQL from the command line: connect, query databases, manage users, repair tables, optimize, everything you keep Googling, one reference.

Upload an ISO to Proxmox three ways: the web UI, wget straight onto the node, or SCP. Which to use when the browser upload stalls, plus checksum verification.