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I erased Windows 7 and installed Ubuntu 12.04 on my Dell Latitude E4200.

I an very happy with my choice but with little pity.

I cannot use the wireless service in my university as the build-in device works unstable. I bought a USB wireless device, which solve the problem.

However, the build-in device keep to sent me message about unable to connect, which waste laptop's cup & battery.

The phsical bottom to turn off wireless affect both devices.

So the question is: "How can I manually shut down wireless device?"

There is another interest comes to my mind: "Does 2 wireless improve the overall internet usage if I run a high-internet-consuming program like BT ?"

Thank for your time and energy.

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up vote 1 down vote accepted

Connect like you normally would (don't worry about the other complaining about not being able to connect for now). Now, open a terminal and type ifconfig.

It should show you your network devices. You'll see lo, eth0, wlan0, wlan1. Look for the wlan that actually has an IP address...this is the one that you want to keep.

So, if wlan1 has the IP, then we want to get rid of wlan0.

Now, type:

sudo nano /etc/rc.local

and scroll down to the very bottom, and just above "exit 0", type

sudo ifconfig wlan0 down 

Hit Ctrl+X, then ENTER to save and exit. On reboot, it should take down the wlan0 interface (the wireless card you don't want) as it starts up.

If later on you decide you want to turn this off, just erase that line.

share|improve this answer
that works. thanks very much. – yi.tang.uni Jan 28 '13 at 20:54

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