How to find the free size currently FileSystem has, on the disk mounted?

I know 'df' lists all the mounted disks, but I am interested to know details
for the filesystem, in which currently I am working.

Just use "df ."

The command df is the one which you want. df does more that just list the mounted file systems, it also tells you where they are mounted, the file type, size of the mounted partition and how much of the partition is used.
For example 'df -h' on my computer gives the following

Filesystem Size Used Avail Use% Mounted on
/dev/hda1 18G 5.6G 12G 34% /
tmpfs 248M 0 248M 0% /dev/shm

This says that hda1 has 5.6 GB free

df -k will give you all info about each mounted

Under HP-UX (10.20) you've also got the bdf command which will give a little saner output if you're coming from a Linux system and are used to the df output given there....

bdf -i . for the current filesystem

Just for info, it's always useful to post the output of "uname -a" so that we know which UNIX variant you're using.

Cheers
ZB

Problem is, I cannot determine some path, is 'mounted on' what.

I already tried df -k. It gives me a complete list.

I want to know something, if I am in /abc/def/ghi

then on which filesystem it is mounted, how much free space, % utilized & so on... only for the filesystem consisting /abc/def/ghi.

uname -a gives following output -
AIX machinename 2 5 0038967C4C00

Perderabo has already supplied the answer.

df -k .

where . = current directory