root📺 Learn Linux. One concept at a time.
Short, practical video lessons on Linux, system administration, troubleshooting, Unix and infrastructure, focused on the “why” behind every command.
Latest reels
Newest first. Each reel links to Instagram.
▶ What rm -rf / really does (and why never to run it)
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▶ “No space left on device” but df shows space: inodes
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▶ Filesystem read-only: why it happens and what to check
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▶ CPU 30% but load HIGH: load average is not CPU
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▶ Slow disk? Find the bottleneck with iostat
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▶ Slow server? Check vmstat
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▶ Deleted the file but the disk is still full (lsof +L1)
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▶ Who is slowing down your server? Start with top
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▶ Zombie processes: dead but still listed
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▶ PID 1: the first process
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▶ kill is not always dead: SIGTERM vs SIGKILL
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▶ Hidden files and ls -la
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▶ Filter logs with grep -i
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▶ The pipe |: chain commands together
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▶ EP12: The PATH variable
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▶ EP11: How package managers work
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▶ EP10: System logs and tail -f
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▶ EP09: SELinux enforcing vs permissive
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▶ EP08: LVM, expand storage with zero downtime
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▶ A rogue app is eating all your RAM: find it and stop it
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▶ start vs enable: why a service did not survive reboot
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▶ sudo vs su: which to use on servers
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▶ Linux file permissions: the chmod numbers to avoid
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▶ What is your UID? Users and the id command
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▶ There is no C: drive: the single root /
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▶ Linux in 60 seconds: kernel, distributions and “everything is a file”
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Explore by topic
Every video has a written version on this site.
🐧 Linux fundamentals
Processes, filesystems, permissions, commands, users and core concepts.
🛠️ Troubleshooting
Disk full, read-only filesystems, high load, services that will not start.
⚙️ System administration
Services, storage, LVM, SELinux, logs and networking.
🌞 Unix
Solaris and HP-UX: ZFS, Zones, LDOMs, LVM and boot.
🤖 Automation
Ansible Automation Platform and Podman containers.
🎯 Interview prep
Questions by topic and level, with a practice mode.