Free space not calculated when LVM is in use

[ascheel]

Free space on the destination filesystem is not calculated properly if an LVM setup is in use. The logic used is 'df -k $DEST' which in my case is:

df -k /media/AV/Movies | tail -1 | awk '{print $4*1024}'

On a standard filesystem, this works just dandy. In LVM, it does not for this reason:

user@host:/media/AV/Movies$ df -k /media/AV/Movies
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_av_main-lv_av_main
7691417892 5133398648 2167346336 71% /media/AV

So the logic will grab the '71%' and parse that as free blocks instead of the proper column indicating free space. I do not have a proper solution to fix this. Perhaps if a '%' is found in the number, then use $3