i assigned a temporary ip address to my eth0 interface using this command

sudo ifconfig eth0 169.254.1.1 netmask 255.255.0.0

as described here

it works fine, when i do ifconfig it shows the newly assigned ip address.

eth0      Link encap:Ethernet  HWaddr 5c:26:0a:4f:32:11  

          inet addr:169.254.1.1  Bcast:169.254.255.255  Mask:255.255.0.0

          inet6 addr: fe80::5e26:aff:fe4f:3211/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:774 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1160 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:170598 (170.5 KB)  TX bytes:218967 (218.9 KB)

          Interrupt:20 Memory:f6900000-f6920000 

i expected this ip address should hold until i flush it out. but soon afterwards it is reset

eth0      Link encap:Ethernet  HWaddr 5c:26:0a:4f:32:11  

          inet6 addr: fe80::5e26:aff:fe4f:3211/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:784 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1202 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:174678 (174.6 KB)  TX bytes:228013 (228.0 KB)

          Interrupt:20 Memory:f6900000-f6920000 

i only need this ip address temporarily and rather not change my /etc/network/interfaces which reads

auto lo

iface lo inet loopback

i am on 12.04, any suggestion would be helpful
thanks

UPDATE

this is my motive. i want to transfer some large files over ethernet. I have laptops with Gigabit capable adapters but slow routers. When both machines are windows i can simply hook them up with a network cable and after some time when they dont find a dhcp server they revert to link-local address of range 169.254.x.x/16 and file transfers would just work. Unfortunately in Ubuntu this does not happen. I have to manually set an ip address. Then the machines can ping each other and can transfer files, but only for a short interval of time.

One thing I can do is keep issuing sudo ifconfig eth0 ... every 30 secs or so to keep things working but this is pretty annoying. I have to do this kind of transfers quite frequently so would rather not take the hassle of modifying etc/network/interfaces everytime.