Terminal is not net application. Maybe is better to say, in your case, terminal is container for net application like ssh, telnet, lftp, wget, lynx ...
Edit your:
sudo -H gedit /etc/profile.d/proxy.sh
Enter the details in this format.
export http_proxy=http://username:password@proxyhost:port/
export ftp_proxy=http://username:password@proxyhost:port/
export telnet_proxy=http://username:password@proxyhost:port/
This is for when using wget, ftp, lftp, telnet in terminal
ssh has no native SOCKS client support, you need to use a ProxyCommand for that, for instance with socat:
ssh -o ProxyCommand='socat - SOCKS4A:myproxy:%h:%p,socksuser=nobody' user@host
Or use things like tsocks to transparently use SOCKS for TCP traffic.
For SOCKS5 with socat 2:
ssh -o ProxyCommand='socat - "SOCKS5:%h:%p|tcp:myproxy:1080"' user@host
For HTTP Proxy CONNECT method with socat 2:
ssh -o ProxyCommand='socat - "PROXY:%h:%p|tcp:myproxy:80"' user@host