Tag: sysadmin

ss replaces netstat on modern Linux: faster, shows more socket detail, and reads from the kernel. Every netstat command you rely on, rewritten for ss.

docker system prune is useful but risky. Learn what each cleanup command does and how to check disk usage safely.

PATH is different in cron, stdout is muted, and MAILTO breaks silently. Learn cron traps and how to debug them.

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.

Master ~/.ssh/config: Host aliases, HostName, User, Port, IdentityFile, ProxyJump. Stop typing long SSH commands. One-line setup.

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

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

Understand Linux umask: what it is, how 022 and 027 work, calculating file permissions, and why it matters for shared directories and security.

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.

Compare zram (compressed RAM) and traditional swap files. Learn when each works, setup, and real-world performance trade-offs for memory-constrained systems.

Use strace to trace system calls and debug mysterious permission errors, missing files, and network issues without ever reading source code.

Master lsof to find port conflicts, trace deleted files eating disk, and debug network connections.