Tag: sysadmin
All the articles with the tag "sysadmin".
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journalctl Queries Every Sysadmin Needs
Essential journalctl commands: -u, -f, --since, -p, -k, -b, --no-pager, JSON output. The queries you need on a broken server at 2 AM.
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Why Your SSH Connection Keeps Dropping
Fix SSH timeouts: ServerAliveInterval, ServerAliveCountMax, ClientAliveInterval. Understand NAT, firewalls, and TCP keepalive.
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ss Is the New netstat (And It's Better)
netstat is deprecated. ss is faster, shows more, and does everything netstat did—better.
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Cleaning Up Docker Disk Space the Right Way
docker system prune is useful but risky. Learn what each cleanup command does and how to check disk usage safely.
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Why Your Cron Job Is Failing Silently
PATH is different in cron, stdout is muted, and MAILTO breaks silently. Learn cron traps and how to debug them.
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The Linux OOM Killer: Why It's Killing Your App
Understand the OOM killer, read dmesg logs, protect critical processes with oom_score_adj.
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The SSH Config File: The Shortcut You're Not Using
Master ~/.ssh/config: Host aliases, HostName, User, Port, IdentityFile, ProxyJump. Stop typing long SSH commands. One-line setup.
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Why the `latest` Docker Tag Is Lying to You
latest doesn't mean newest. Learn why pinning versions and digests matter for reproducible deployments.
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Why kill -9 Is the Wrong Default
Signals explained: SIGTERM vs SIGKILL, graceful shutdown, and when to actually use kill -9.
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The umask You've Been Ignoring
Understand Linux umask: what it is, how 022 and 027 work, calculating file permissions, and why it matters for shared directories and security.
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/proc as a Debugging Tool
The /proc filesystem is a window into running processes. Learn to use it without extra tools.
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zram vs Swap: What's Actually Faster for Low-RAM Servers
Compare zram (compressed RAM) and traditional swap files. Learn when each works, setup, and real-world performance trade-offs for memory-constrained systems.