I want to use the Ubuntu Software Center to install software, but I can not download them.
How can I give my proxy settings in Ubuntu terminal (just like we use cmd in Windows to choose IE proxy settings)?
You can easily change the proxy settings for your user, or for the entire system, within the Network config under System Settings. This uses the GUI and is quick and helpful, but not very advanced. If you have particular requirements or special settings/circumstances, this may not do everything you need.
You should be all set. You may have to logout and login again for changes to take affect. In unusual circumstances, you may have to reboot your system, but that is highly unlikely for a Linux system.
proxy setting from terminal in ubuntu:
For a HTTPs and FTP
If there is no username and password required for your proxy then simply remove the username and password section.
These settings are saved into /etc/apt/apt.conf file .So you can directly add these variables using text editor .First open the apt.conf file
then enter the username,password,proxy_ip and port in given format