how to get the permissions of any filesystems
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what does it mean?
"permission denied while opening filesystem"

through commands can we give/get permissions of file systems

Have you tried opening filesystem as root?

i have tried with thunar and when i got to the top of current filesysten i could right click and there was "filesystem properties dialog"

It means your login doesn't have either read,write or execute access to the data. Access can be give to you by ether root or owner.
Read on the whole permissions subject:
http://wiki.debian.org/Permissions

read man pages too, type in terminal:
man chmod
man chown

What type of filesystem are you talking about? Is it a pen drive? Do you need to mount it?

An NTFS or FAT32 filesystem doesn't contain linux permissions, so you will need to add man mount.vfat and man mount.ntfs to your reading list. Look at the uid, gid, fmask and dmask options which determine the permissions for files and directories on the entire filesystem.

From your description, you may be trying to change the permissions of a system directory or of the root partition. The answer is simply don't. Regular users shouldn't have write access to these areas.

for permissions:
Case 1: for files
$ls -l
sample o/p

-rw-rw-r-- 1 ashwini ashwini 170803 Jan 29 14:27 shell-20110129-6.ogv
drwxrwxr-x 2 ashwini ashwini 4096 Dec 28 14:08 sketchbook

now the left most column shows d, r, w, x that means: directory, read, write, and execute. for root, user and the user who created(I am not sure about the third one). Here for changing the permissions you can use "chmod" command.

Case 2: for file systems
When you mount file systems , they can be mounted as read only, read write and read write execute mode. If you are having some executable files like shell script on a non-executable mounted file systems then you can not execute the shell script. For such cases, you will have to either modify /etc/fstab or you will have to check the options in mount command through which you are mounting the file system. If you are using ubuntu then you can install some application which will take care of this graphically.