df

show file system type

df -T /
df -T /mnt

output:

Filesystem     Type  1K-blocks      Used Available Use% Mounted on
/dev/md0       btrfs 499973440 110767024 383516256  23% /

Filesystem     Type 1K-blocks     Used Available Use% Mounted on
/dev/vda1      ext4  24476576 12632896  10516636  55% /