I have raised this question previously but none of the solutions work on the mounted points. Neither du nor df work on the mounted points. Is there a way to find it out?
I don't understand what you mean by "doesn't work on the mount points". Change into the directory where you want to untar (if not already there) and execute:
df . | grep -v '^Filesystem' | awk 'NF=6{print $4}NF==5{print $3}{}'
The grep gets rid of the header and the awk prints out the kilobytes available for both split and no-split lines.
This is based on the following sort of output, you may have to adjust if your UNIX outputs something different:
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda4 206434224 56965356 139065176 30% /
varrun 1037296 132 1037164 1% /var/run
varlock 1037296 0 1037296 0% /var/lock
udev 1037296 68 1037228 1% /dev
devshm 1037296 12 1037284 1% /dev/shm
/dev/sda2 93327 43535 44973 50% /boot
/dev/sdc1 155056484 29417456 117824612 20% /media/extra160
gvfs-fuse-daemon
206434224 56965356 139065176 30% /home/pax/.gvfs