how to execute this program?

Filesystem 1024-blocks Free %Used Iused %Iused Mounted on
/dev/hd4 32768 16016 52% 2271 14% /
/dev/hd2 4587520 1889420 59% 37791 4% /usr
/dev/hd9var 65536 12032 82% 518 4% /var
/dev/hd3 819200 637832 23% 1829 1% /tmp
/dev/hd1 524288 395848 25% 421 1% /home
/proc - - - - - /proc
/dev/hd10opt 65536 26004 61% 654 4% /opt

i used df -k to display amount of available disk space for my filesystem..my filesystem has more than 12disks in it. i wanted to extract the 4th column alone, which contains %used in the disks in my filesystem and also to chk which disk has the %used more than 80% and enter into an new file...:confused:

df -k | awk '{print$4}' >>newfile.out

i successfully extracted the 4th column (i.e)%Used, but was not able to chk out which is above 80% in the %Used column...

i need the ur help... :frowning:

awk 'int($4)>80{print}' file > newfile

Regards