Create an XML file named border.xml in the drawable folder and put the following code in it.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="#FF0000" />
</shape>
</item>
<item android:left="5dp" android:right="5dp" android:top="5dp" >
<shape android:shape="rectangle">
<solid android:color="#000000" />
</shape>
</item>
</layer-list>
Then add a background to your linear layout like this:
android:background="@drawable/border"
EDIT :
This XML was tested with a galaxy s running GingerBread 2.3.3 and ran perfectly as shown in image below:
ALSO
tested with galaxy s 3 running JellyBean 4.1.2 and ran perfectly as shown in image below :
Finally its works perfectly with all APIs
EDIT 2 :
It can also be done using a stroke to keep the background as transparent while still keeping a border except at the bottom with the following code.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:left="0dp" android:right="0dp" android:top="0dp"
android:bottom="-10dp">
<shape android:shape="rectangle">
<stroke android:width="10dp" android:color="#B22222" />
</shape>
</item>
</layer-list>
hope this help .