Package Management

apt update

• Refreshes package repository lists
• Run before installing packages

apt upgrade

• Updates all installed packages
• Use -y flag for non-interactive

apt install [package]

• Installs specified package
• Resolves dependencies automatically

apt remove [package]

• Removes package, keeps config files

apt purge [package]

• Removes package and config files

System Information

uname -a

• Shows kernel and system info
• Architecture, version, hostname

lsb_release -a

• Displays Debian version details
• Codename and description

df -h

• Shows disk space usage
• Human readable format

free -h

• Displays memory usage
• RAM and swap information

Process Management

ps aux

• Lists all running processes
• Shows PID, CPU, memory usage

top

• Real-time process monitor
• Press q to quit

systemctl status [service]

• Shows service status
• Active, inactive, failed states

systemctl start [service]

• Starts specified service

systemctl stop [service]

• Stops specified service

Example Package Install

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sudo apt update
sudo apt install nginx
sudo systemctl enable nginx
sudo systemctl start nginx