Linux Package Management Tips

1) To check if a package is available in repositories and if so available, to check the version and size of the package, as super user run the following commands in respective distro:
Fedora,CentOS: yum list <package_name>
Ubuntu/Debian: aptitude search <package_name>
OpenSuse : zypper search <package_name>

2) To know the number and name of the packages installed
Fedora,CentOS,OpenSuse: rpm -qa
Ubuntu/Debian : dpkg -l

3) To list the repositories used for fetching the packages
Fedora : yum repolist
Ubuntu/Debian : cat /etc/apt/sources.list
OpenSuse : zypper repos