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To view/add partitions in linux they must be mounted. To mount a partition means to place the partition on a directory for accessibility. So...
Since we know what partition it is (hdb5) we'll move along quickly. First make an empty directory, preferably in the /mnt directory, so as root type:
And then we need to know what filesystem is on the drive. Assuming it's ext3 you would mount it with:
mount -t ext3 /dev/hdb5 /mnt/hdb5
See man mount for more information on that. After you get it mounted to your liking it's time to put it in your /etc/fstab file. So an entry in there might look like this (for an ext3 filesystem):
/dev/hdb5 /mnt/hdb5 ext3 defaults 2 1
So let us know what filesystem is on the drive for more specific info