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 |