Linux System Administration

Overview

Core commands and best practices for Linux system administration, including system information viewing, resource monitoring, service management, etc.

System Information

Basic Information

System version

cat /etc/os-release uname -a

Hostname

hostnamectl

Uptime and load

uptime

Hardware Information

CPU information

lscpu cat /proc/cpuinfo

Memory information

free -h cat /proc/meminfo

Disk information

lsblk df -h

Resource Monitoring

Real-time Monitoring

Comprehensive monitoring

top htop

Memory monitoring

vmstat 1

IO monitoring

iostat -x 1 iotop

Network monitoring

iftop nethogs

Historical Data

System activity report

sar -u 1 10 # CPU sar -r 1 10 # Memory sar -d 1 10 # Disk

Service Management

Systemd Services

Service status

systemctl status service-name systemctl is-active service-name

Start/Stop services

systemctl start/stop/restart service-name

Boot startup

systemctl enable/disable service-name

View all services

systemctl list-units --type=service

Common Scenarios

Scenario 1: System Health Check

Quick health check script

echo "=== System Load ===" && uptime echo "=== Memory Usage ===" && free -h echo "=== Disk Usage ===" && df -h echo "=== Failed Services ===" && systemctl --failed

Scenario 2: Troubleshoot High Load

1. Check load

uptime

2. Find high CPU processes

ps aux --sort=-%cpu | head -10

3. Find high memory processes

ps aux --sort=-%mem | head -10

Troubleshooting

Problem Commands

System lag top , vmstat 1 , iostat -x 1

Disk full df -h , du -sh /* , ncdu

Memory shortage free -h , ps aux --sort=-%mem

Service abnormal systemctl status , journalctl -u