Find the type of file system, in Linux

Try the following:

#blkid -o value -s TYPE /dev/sda1
ext4

Or, for mounted partitions:

df -T
Filesystem     Type     1K-blocks     Used Available Use% Mounted on
rootfs         rootfs    20026236 20009848         0 100% /
/dev/root      ext4      20026236 20009848         0 100% /
devtmpfs       devtmpfs   1010720        0   1010720   0% /dev
tmpfs          tmpfs       202252      212    202040   1% /run
tmpfs          tmpfs         5120        0      5120   0% /run/lock
tmpfs          tmpfs       509140        0    509140   0% /dev/shm
/dev/sda2      ext4     459913320    71736 436456292   1% /home