Here are the simple steps for searching, installing, or/and removing packages:
1. To search Adobe Flash Plug-in for Firefox browser:
$ sudo apt-cache search flash
Above apt-cache command displays a list of all packages including the word "flash". There is no need for sudo as apt-cache makes no changes to your system. You can also simply try:
$ apt-cache search flash
2. If you wanted to search more than one keyword for example “adobe flash plugin”, you could input
$ apt-cache search adobe flash plugin
flashplugin-nonfree-extrasound - Adobe Flash Player platform support library for Esound and OSS
pyjamas - Python web widget toolkit and Python-to-Javascript compiler
konqueror-nsplugins - Netscape plugin support for Konqueror
flashplugin-installer - Adobe Flash Player plugin installer
flashplugin-downloader - Adobe Flash Player plugin installer (transitional package)
3. To Install a Package: for example 'flashplugin-installer' (as searched above), type the following:
$ sudo apt-get install flashplugin-installer
To install multiple packages, just specify packages separated by spaces. Example: For installing Compiz Fusion 3D desktop:
$ sudo apt-get install compiz compiz-gnome compizconfig-settings-manager compiz-fusion-plugins-extra libcompizconfig0 compizconfig-backend-gconf fusion-icon pdfcube
4. To Remove a Package:
$ sudo apt-get remove eclipse