Determining whether a mounted disk has a file system on it

Firstly identify which disk we are after with fdisk:

fdisk -l

we can also check for disk and partitions with lsblk

lsblk

And finally check whether there is a file system on the disk / partition:

file -s /dev/sda1

To create a file system we can use the mkfs utility:

mkfs -t ext4 /dev/sda1

and to mount it temporarily:

mkdir -t /mount/partition1
mount -t auto /dev/sda1 /mount/partition1

or to mount it permenently:

sudo vi /etc/fstab

and add the following line:

/dev/sda1    /mount/partition1    auto    auto,nouser,exec,rw,async,atime    0 0