Linux & System Administration

Analyzing Linux boot logs: terminal displaying journalctl and dmesg output with timestamps, error warnings highlighted, grep filters, boot sequence and troubleshooting notes. & fixes

Graphic showing the basics of setting up an Ubuntu web server: terminal with apt install and systemctl, site files(HTML) in /var/www, browser at http://localhost, and config files.

Quick guide: find large Linux files fast with du, find, ncdu; use du -ah --max-depth=1 | sort -hr or find / -type f -size +100M -exec ls -lh {} + to free disk. to delete or archive

Hyperreal cinematic scene: cracked padlock on manila folder, spilled glowing file icons and torn permission tokens; puzzled admin with wrench left, shadowy intruder at server right

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Diagram showing enabling SSH key authentication on Linux: gen key pair, copy pubkey to server (~/.ssh/authorized_keys), set perms, disable password auth, restart sshd, test login..

Guide image showing methods to check active network ports and open connections across systems: use netstat/ss/lsof on Unix, Resource Monitor or netstat on Windows, and firewall checks.

Illustration of systemctl commands: start, stop, restart, enable, disable, status, is-active; managing units and services on systemd Linux with command examples, service lifecycle.

Illustration of configuring UFW: enable firewall, allow SSH, allow ports/apps, set default deny incoming, enable logging, verify status and manage rules with commands via CLI tools.

Graphic showing cron concept: terminal with crontab lines, clock, calendar and gears representing scheduled, recurring automated jobs and system maintenance tasks run by cron. now.

Illustration of system cleanup: removing temporary files cache and old log files to free disk space, showing progress bar, file icons being deleted and increased available storage.

Illustration of safe package maintenance: backup, check changelogs, update package lists, test in staging, run upgrades with confirmations, verify services and restore if issues occur.!!