Installing application from terminal isn't hard as it seams.
To open terminal in ubuntu linux go to applications-accessories-terminal
Than to install type in :
sudo apt-get install nameofyourapplication(like firefox or vlc)
Than type in root password if your asked,and it will start in few seconds it will ask you do you want to continued to continue so type Y and it will install that application.
Now to uninstall application type in:
sudo apt-get purge nameofyourapplication(like firefox or vlc)
and again type in root password if asked and type in Y to continue when asked.
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