nslookup on Linux: DNS Lookup for A, AAAA and MX Records
Use nslookup on Linux for DNS troubleshooting: query A and AAAA records, specify resolver, compare with dig and…
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Linux bash history Command: Search, Re-run and HISTSIZE Settings
Use bash history on Linux: history, !number, Ctrl+R search, HISTSIZE and HISTFILESIZE, append vs overwrite, and secure history…
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iperf3 on Linux: Test Network Bandwidth Between Two Servers
Run iperf3 on Linux to measure TCP/UDP throughput: start server with iperf3 -s, client iperf3 -c, parallel streams,…
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curl POST JSON on Linux: Call REST APIs from the Terminal
Send JSON POST requests with curl on Linux: Content-Type application/json, -d body, bearer tokens, pretty print with jq,…
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Make sysctl Changes Persistent on Linux (/etc/sysctl.d)
Apply persistent kernel tuning on Linux: sysctl -w, /etc/sysctl.d/*.conf, sysctl --system, common net.ipv4 settings, and verify after reboot.
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fsck on Linux: Repair ext4 File Systems Safely (Unmount First)
Use fsck on Linux to check and repair ext4: unmount filesystem, fsck -f /dev/sdXn, emergency boot single-user, e2fsck…
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smartctl on Linux: Check Disk Health (SMART Attributes and Tests)
Run smartctl on Linux to read SMART disk health: smartctl -a, PASSED/FAILED, self-tests, schedule short/long tests, and when…
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nc (netcat) on Linux: Test Open Ports and Simple TCP Debugging
Use nc netcat on Linux to test if a port is open: nc -zv host port, listen with…
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mtr Command on Linux: Network Diagnostics (Better Than ping + traceroute)
Use mtr on Linux to measure packet loss and latency hop-by-hop: install mtr, mtr hostname, report mode, and…
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logrotate on Linux: Configure Log Rotation (/etc/logrotate.d)
Configure logrotate on Linux: /etc/logrotate.conf, per-app files in logrotate.d, daily/weekly rotation, compress, copytruncate, and test with logrotate -d.
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