Get different information about program on debian os

debian.sh

# Get list of available packages on your operating system
dpkg --get-selections

# To check whether a package is installed or not:
get --get-selections {prg_name}

# Search for a filename comes from which package
dpkg -S `which ifconfig`

# List files installed to your system from package-name.
dpkg --listfiles/-L {pkg_name}

# List contents of a deb package.
dpkg --contents/-C foo.deb

# Find all dependencies of a package
apt-cache depends foo.deb

# List different version of a pacakge on repo
apt-cache policy foo