file -s

Install legacy :-

[root@localhost baz]# grub-install --root-directory=/maingrub /dev/sda1
Installation finished. No error reported.
This is the contents of the device map /maingrub/boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.

(fd0)   /dev/fd0
(hd0)   /dev/sda
(hd1)   /dev/sdb
(hd2)   /dev/sdc

[root@localhost baz]# file -s /dev/sda
/dev/sda: x86 boot sector; GRand Unified Bootloader, stage1 version 0x3, stage2 address 0x2000, stage2 segment 0x200; partition 1: ID=0x83, active, starthead 1, startsector 63, 6143697 sectors; partition 2: ID=0x5, starthead 15, startsector 6143760, 1470798000 sectors, code offset 0x63

Install grub2 :-

[root@localhost baz]# grub2-install --root-directory=/maingrub /dev/sda
Installation finished. No error reported.

[root@localhost baz]# file -s /dev/sda
/dev/sda: x86 boot sector; GRand Unified Bootloader, stage1 version 0x3, stage2 address 0x2000, stage2 segment 0x200; partition 1: ID=0x83, active, starthead 1, startsector 63, 6143697 sectors; partition 2: ID=0x5, starthead 15, startsector 6143760, 1470798000 sectors, code offset 0x63