Command line option to check which filesystem I am using?

mount:

me@hostname:/$ mount
/dev/sda1 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)

...

Found a solution in ubuntuforums: blkid

System disk:

sudo blkid /dev/sda1
/dev/sda1: UUID="...." TYPE="ext4"

External USB disk:

sudo blkid /dev/sdf1
/dev/sdf1: LABEL="backup" UUID="..." TYPE="ext3"     

mdadm RAID:

sudo blkid /dev/md0
/dev/md0: LABEL="raid" UUID="..." TYPE="ext4" 

Mount without specifying filesystem (commenting out any entries in fstab) works as well:

sudo mount /dev/sdf1 /mnt/tmp
mount | grep /mnt/tmp
/dev/sdf1 on /mnt/tmp type ext3 (rw)

df -h -T will list all disks used with filesystem type.