Tag: sysadmin

Is Your Linux Server Destroying Its SSD?

Check SSD health, find excessive write patterns, use noatime, move logs to tmpfs to extend lifespan.

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.

Why Your SSH Connection Keeps Dropping

Fix SSH timeouts: ServerAliveInterval, ServerAliveCountMax, ClientAliveInterval. Understand NAT, firewalls, and TCP keepalive.

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.

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.

The Linux OOM Killer: Why It's Killing Your App

Why Linux kills your app with no warning. Understand the OOM killer, read dmesg logs, and shield critical processes with oom_score_adj and swap.

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.

Why the `latest` Docker Tag Is Lying to You

latest doesn't mean newest. Learn why pinning versions and digests matter for reproducible deployments.

Why kill -9 Is the Wrong Default

Signals explained: SIGTERM vs SIGKILL, graceful shutdown, and when to actually use kill -9.

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.

/proc as a Debugging Tool

The /proc filesystem is a live window into every running process on Linux. Debug PIDs, file descriptors, memory, and limits with no extra tools installed.

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.