Ubuntu

Search for packages.

http://www.ltsp.org/twiki/bin/view/Ltsp/WebHome

Prepare ltsp environment.

sudo cp /etc/apt/sources.list /opt/ltsp/i386/etc/apt/sources.list
sudo chroot /opt/ltsp/i386
apt-get update

Installed packages.

dpkg --get-selections
apt-get install openssh-client openssh-server

List packages on one machine and install on another.

dpkg --get-selections > installed-software
dpkg --set-selections < installed-software
dselect

Upgrade.

sudo apt-get -y update
sudo apt-get -y upgrade

Which package provides.

http://packages.ubuntu.com/

List available linux packages.

apt-cache pkgnames