how to get active interfaces in ubuntu

Question

i am trying to extract only the active interfaces on my machine,i have a script that auto connect and disconnect running,and the interfaces are like this when i run ifconfig

tun1      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:10.9.8.1  P-t-P:10.9.8.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:13 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:2262 (2.2 KiB)  TX bytes:1819 (1.7 KiB)

tun 5
tun 7 
...etc

how can i extract only the interface names

Answer 1

ifconfig | grep "Link encap" | awk '{ print $1 '}