I know how to mount an iso image under Linux. But, how do I unmount the same under Linux?
You need to use the umount command detaches the file system(s) mentioned from the file hierarchy. A file system is specified by giving the directory where it has been mounted. Giving the special device on which the file system lives may also work, but is obsolete, mainly because it will fail in case this device was mounted on more than one directory.
List Your Currently Mounted File System
Either use df or mount command as follows:
# df -H
Unmount an ISO Image
Type the following command (assuming that your image is mounted at /mnt/iso):
# umount /mnt/iso
You can also force unmount (if it is giving some error), enter:
# umount -f /mnt/iso