How to determine, with certainty, the filesystem type of a partition from the outputs of the Linux "file -s" command?

My problem is to *decode* the output of the command file -s /dev/sdX on my system (where /dev/sdX is the device file associated to a USB key). Below I'll show the output of the command file -s /dev/sdX where the device file /dev/sda1 is a partition formatted with a FAT32 filesystem, while the device /dev/sdb is a partition formatted with a NTFS filesystem. ### Output of file command for a FAT32 filesystem ### In the case of the FAT32 filesystem the output of the file command is:

> file -s /dev/sda1
/dev/sda1: DOS/MBR boot sector, code offset 0x58+2, OEM-ID "mkfs.fat", sectors/cluster 8, Media descriptor 0xf8, sectors/track 62, heads 31, hidden sectors 2048, sectors 1966080 (volumes > 32 MB), FAT (32 bit), sectors/FAT 1920, reserved 0x1, serial number 0x4ba3ff5b, unlabeled

In the output is present the information , FAT (32 bit), sectors/FAT 1920, which could be enough to say that the filesystem type is FAT32, but in the next paragraph I'll show that the string FAT is also present in the output of the file command in the case of an NTFS filesystem. ### Output of file command for a NTFS filesystem ### In the case of a NTFS filesystem the output of the file command is:

> file -s /dev/sdb 
/dev/sdb: DOS/MBR boot sector, code offset 0x52+2, OEM-ID "NTFS    ", sectors/cluster 8, Media descriptor 0xf8, sectors/track 63, heads 255, dos  file -s /dev/sdf
/dev/sdf: DOS/MBR boot sector

In this case exfat is not present in the output. ### Output of file for ext4 ###

file -s /dev/sdb1
/dev/sdb1: Linux rev 1.0 ext4 filesystem data, UUID=38bc3d5b-381e-4f19-8640-c77d9483882b (needs journal recovery) (extents) (64bit) (large files) (huge files)

In this case is present the info ext4 filesystem data,. In these 4 examples (FAT32, NTFS, EXFAT, EXT4) the output of the file command appears very different for different filesystem types, so it is difficult to find a simple rule to decide the filesystem type by this output. ___ **EDIT** To clarify why I'm trying to use the file command *to get information about the filesystem type of a USB*, please read [this post](https://unix.stackexchange.com/questions/794029/how-to-find-the-filesystem-type-of-the-partition-of-an-usb-before-mount-it) .