One can find out BIOS version under for Linux Box using the dmidecode command which is a great tool to analyse BIOS data.

Dmidecode command helps you to find out the BIOS version without rebooting the server.

root@server ] dmidecode –type 0

dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
Vendor: American Megatrends Inc.
Version: 2.0
Release Date: 04/24/2014
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 16384 kB
Characteristics:
PCI is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
BIOS ROM is socketed
EDD is supported
5.25″/1.2 MB floppy services are supported (int 13h)
3.5″/720 kB floppy services are supported (int 13h)
3.5″/2.88 MB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
ACPI is supported
USB legacy is supported
BIOS boot specification is supported
Targeted content distribution is supported
UEFI is supported
BIOS Revision: 4.6


OR

root@server ] dmidecode -s bios-version
2.0