Tag: sysadmin

PostgreSQL + Linux: Kernel Tuning That Actually Matters

An AWS engineer found Linux 7.0 halved their PostgreSQL performance. The fix was kernel tuning. Here's what settings matter and why, so you're not the last to know.

Proxmox NAT Bridge: One IP, Many VMs

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

Linux Privilege Escalation: The Defensive Playbook

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.

Adding Extra Swap to Linux

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.

Directory FileCount

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.

Find out whats taking up all the hdd space

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.

Linux su with custom shell

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

Logrotate & Compression

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

MySQL CLI: From Connection to Maintenance

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

Three ways to upload ISOs to Proxmox

Three ways to upload an ISO to Proxmox — web UI, wget direct download, or SCP from the CLI. When each one wins, plus storage paths and checksum verification.

Recursively delete all empty subdirectories

Clean up empty directories with find and rmdir — safely prune orphaned dirs left after file migrations.

Remove all old installed but unused kernels

Old kernels pile up in /boot and eat disk space — safely remove unused kernels on Ubuntu and Debian with apt and dpkg.