🖥️ System Administration

SSH offers every key you own and the server cuts you off after six. Pin one key with IdentitiesOnly, and learn why GitHub gives a different error.

SSH stops with "Host key verification failed." Read the warning correctly, decide whether the key really changed, and fix it without disabling checking.

How do I set up my shell and directory structure? What tools do I need for this? And what's the process for starting up my shell?

The best package manager is Homebrew. Learn how to install, use, auto update, and contribute to Homebrew.

Learn how to install Rocky Linux, a community-driven enterprise Linux distribution. Includes detailed installation steps, system configuration, and post-installation setup for development.

Send Linux system email to Gmail: create an app password, configure mail.rc for mailx or s-nail, or use msmtp, then route cron and systemd alerts to your inbox.

Learn how to manage multiple GitHub accounts on one computer using SSH keys. Includes step-by-step instructions, shell functions, and best practices for macOS.

Learn systemd by doing: the systemctl commands you need daily, reading logs with journalctl, writing a service unit, and replacing a cron job with a timer.

How to deliver macOS system mail to Gmail by relaying Postfix through Gmail's SMTP server so cron jobs and background tasks can email you when they fail.

Install bash on windows for fun and profit. Learn how to install it with various methods. Learn about the benefits it will provide.

Fix "Permission denied (publickey)" in SSH and Git: use the git user, load your key into ssh-agent, add it to GitHub, and set key file permissions.

Step-by-step guide to set up Pi-hole ad blocker on your Synology NAS using Docker. Learn how to configure network-wide ad blocking and DNS filtering.