System Maintenance

System Updates

Regular Updates

sudo apt update          # Update package lists
sudo apt upgrade         # Upgrade packages
sudo apt full-upgrade    # Full upgrade with dependency changes
sudo apt autoremove      # Remove unused packages
sudo apt autoclean       # Clean package cache

Security Updates

sudo apt install unattended-upgrades
sudo dpkg-reconfigure unattended-upgrades

Kernel Updates

uname -r                # Check current kernel
sudo apt install linux-image-amd64  # Install latest kernel

Log Management

System Logs

/var/log/syslog: General system log
/var/log/auth.log: Authentication log
/var/log/kern.log: Kernel messages
/var/log/dmesg: Boot messages

Viewing Logs

tail -f /var/log/syslog  # Follow log in real-time
journalctl              # Systemd journal
journalctl -u service   # Service-specific logs

Log Rotation

Configured in /etc/logrotate.conf and /etc/logrotate.d/

Disk Management

Disk Usage

df -h                   # Filesystem usage
du -h /home             # Directory usage
du -sh *                # Current directory usage

Disk Cleanup

sudo apt autoremove     # Remove unused packages
sudo apt autoclean      # Clean package cache
sudo journalctl --vacuum-time=7d  # Clean old logs
find /tmp -type f -mtime +7 -delete  # Remove old temp files

SMART Monitoring

sudo apt install smartmontools
sudo smartctl -a /dev/sda  # Check disk health

Memory Management

Memory Usage

free -h                 # Memory and swap usage
vmstat 1                # Virtual memory stats

Swap File

sudo fallocate -l 1G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Service Management

Systemd

sudo systemctl status service    # Check service status
sudo systemctl start service    # Start service
sudo systemctl stop service     # Stop service
sudo systemctl restart service  # Restart service
sudo systemctl enable service   # Enable at boot
sudo systemctl disable service  # Disable at boot

Service Logs

sudo journalctl -u service
sudo journalctl -f -u service   # Follow logs

Backup Strategies

Full System Backup

sudo tar -czpf /backup/full-backup-$(date +%Y%m%d).tar.gz --exclude=/proc --exclude=/sys --exclude=/dev --exclude=/mnt --exclude=/tmp --exclude=/backup /

Incremental Backups

Use tools like rsync: bash rsync -av --delete /source /backup

Automated Backups

Use cron jobs or tools like borgbackup.

Monitoring Tools

htop

sudo apt install htop
htop

iotop

sudo apt install iotop
sudo iotop

nmon

sudo apt install nmon
nmon

Performance Tuning

Kernel Parameters

Edit /etc/sysctl.conf: vm.swappiness=10 # Reduce swap usage net.ipv4.tcp_tw_reuse=1 # Reuse TIME_WAIT sockets

Apply changes: bash sudo sysctl -p

CPU Governor

cpupower frequency-info
cpupower frequency-set -g performance  # High performance
cpupower frequency-set -g powersave    # Power saving

Security Hardening

SSH Hardening

Edit /etc/ssh/sshd_config: PermitRootLogin no PasswordAuthentication no AllowUsers youruser

Firewall

sudo apt install ufw
sudo ufw enable
sudo ufw allow ssh
sudo ufw allow 80
sudo ufw allow 443

Fail2Ban

sudo apt install fail2ban

Hardware Monitoring

Sensors

sudo apt install lm-sensors
sensors-detect
sensors

CPU Temperature

sudo apt install psensor

Practice Exercises

Update your system and check for security updates.
Monitor system logs for any errors.
Check disk usage and clean up unnecessary files.
Set up automated backups.
Configure basic firewall rules.
Monitor system performance with htop.

Next, we'll cover advanced topics.