https://drive.google.com/file/d/1iCy_wkZePV-JjJs2tVoH07h5QcmumdkL/view?usp=sharing

1. Overview of Package Management Systems

💡 Key Concept:

• Low-level tools (dpkg, rpm) handle single packages (no dependencies)
• High-level tools (apt, dnf) resolve dependencies automatically

2. Debian/Ubuntu Package Management

Low-Level: dpkg

# List installed packages
dpkg -l
dpkg -l | wc -l                 # Count installed packages
dpkg -l apache2                 # Search specific package

# Find which package owns a file
dpkg -S /usr/share/doc/rsync   # File path
dpkg -S rsync                   # Filename

# List files in a package
dpkg -L apache2

# Install/remove packages (no dependencies!)
sudo dpkg -i package.deb        # Install
sudo dpkg -r apache2            # Remove (keep config)
sudo dpkg -P apache2            # Purge (remove config too)

High-Level: apt

# Update package lists
sudo apt update

# Install/remove packages
sudo apt install apache2
sudo apt remove apache2         # Keep config
sudo apt purge apache2          # Remove config

# Search packages
apt-cache search apache2
apt list --installed | grep apache

# Clean package cache
sudo apt clean                  # Remove all .deb files
ls /var/cache/apt/archives/     # Package cache location

Advanced: aptitude

sudo aptitude update
sudo aptitude safe-upgrade      # Safe system upgrade
sudo aptitude install apache2
sudo aptitude search apache2
sudo aptitude purge apache2

# View repositories
cat /etc/apt/sources.list

Adding Repositories

# Add repository
sudo add-apt-repository ppa:repository/name

# Add GPG key
wget -qO - <https://repo.example.com/key.gpg> | sudo apt-key add -

3. RHEL/Fedora Package Management

Low-Level: rpm

# Query packages
rpm -qa                         # List all installed
rpm -qa | wc -l                 # Count packages
rpm -qa | grep samba            # Search packages
rpm -qi httpd                   # Package info

# Install/remove (no dependencies!)
sudo rpm -ivh package.rpm       # Install (-v=verbose, -h=progress)
sudo rpm -e httpd               # Remove
sudo rpm -Uvh package.rpm       # Upgrade

# Package database location
ls /var/lib/rpm                 # RPM database

# Extract RPM contents
rpm2cpio package.rpm | cpio -t   # List files in RPM
rpm2cpio package.rpm > package.cpio  # Convert to cpio archive

High-Level: dnf (RHEL 8+) / yum (RHEL 7)