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.
Tag: sysadmin
All the articles with the tag "sysadmin".
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
Understand the OOM killer, read dmesg logs, protect critical processes with oom_score_adj.
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 window into running processes. Learn to use it without extra tools.
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.
strace for Beginners: See What Any Process Is Doing
Use strace to trace system calls and debug mysterious errors without reading source code.
lsof: The Tool That Shows You Everything
Master lsof to find port conflicts, trace deleted files eating disk, and debug network connections.
Docker Exit Codes: Why Your Container Keeps Restarting
Decode Docker exit codes: 0 (success), 1 (app error), 125/126/127 (Docker errors), 137 (OOM), 143 (SIGTERM). Debug restarts in minutes.