Setting http_proxy value to local bashrc file

When I connect my laptop to internet from my institute I had to connect it through proxy. But when I connect it from my room I have to connect it directly. So I have to change my proxy frequently.
But I have observed that changing proxy through network manager does not actually change the value of "http_proxy" variable. Neither the export command actually work. So we have changed the value by changing the ~/.bashrc file and adding the proxy value. Use the following command to edit file.

$gedit ~/.bashrc

Then add the following line

http_proxy="http://userid:pass_word@proxy:port/"
https_porxy="https://userid:pass_word@proxy:port/"
ftp_proxy="ftp://userid:pass_word@proxy:port/"

You can also set the domain which should not use proxy by no_proxy environment variable. This will be coma separated string containing domain name. Like

 no_proxy="first.domain,secon.domain"

you can also edit some other file like

/etc/environment
/etc/bash.bashrc
/etc/profile
/etc/.bashrc

To change the proxy that uses by apt when run the following command

 $sudo apt-get update 
$sudo apt-get install 

 we have to change the following file

/etc/apt/apt.conf

In this case you have to specify the proxy in the following way

Acquire::http::proxy "http://userid:pass_word@proxy:port/";
Acquire::https::proxy "https://userid:pass_word@proxy:port/";
Acquire::ftp::proxy "ftp://userid:pass_word@proxy:port";

That's all

Cheers
A.Paul