Linux administration, troubleshooting, Bash scripting, systemd, performance and Linux fundamentals
I ran into this on a test box a while back. I had opened port 80 with ufw allow 80. Later I added iptables -A INPUT -p tcp –dport 80 -j DROP because a guide told me to. Port 80 stayed open. So I tried again, this time inserting the rule at the top of…
Getting “bash: command not found” in Linux? A practical checklist: typos, PATH, cron and non-login shells, sudo’s secure_path, uninstall history and shadowed binaries.
NTFS, exFAT, APFS/HFS+ and ext4 compared, which operating systems can read and write each, and which to pick for USB drives, Macs and Linux servers.
Use apt and dnf like production ops: updates, holds, repos, cleanup, and “what changed?” — not student homework installs.
systemd units, journals, restarts, and timers the way junior admins meet them on the job — practical, not encyclopedia.
Practical Bash for ops automation: readable scripts, safe defaults, exit codes, and habits that survive 2 AM — not CTF cleverness.
set -euo pipefail, traps, and logs that help at 2 AM — practical Bash error handling for sysadmins.
Practical grep, awk, and sed for sysadmins on real log shapes — nginx, auth, journal — without one-liner worship.
Wrap Bash scripts for cron with locks, PATH, logs, timeouts, and exit codes — so night jobs stay boring.
Users, groups, sudo, and permissions the way ops uses them at work — less theory fog, more “why can’t this service write here?”