So the question is, how do I print the first field from the first and second lines of a file?

This is more concise:

hoping near equal.
still i didnt get the exact output i want.

$hostname
datas

$for i in `hostname`
do
grep $i /etc/hosts |awk '(NR == 1 || NR == 2) { print $1,$2 }' > output
tail -1 output
ifconfig lan1 $i
done

this is the sample script. So what i want to change my current lan config to backup lan config.
datas is my curerent
data1 is my backup,

how iwll i do that?

Drop the grep. And the for loop. If you just want the second line then say so.

Try it with echo in front to verify that it does what you want before you deploy it.