How do I determine whether a particular running Ubuntu system was booted using EFI/UEFI, or BIOS?
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Interesting question. Not an exact dupe but try the answer here, to a similar question. – Tom Brossman Jul 11 '12 at 21:10
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2http://unix.stackexchange.com/questions/148356/how-to-know-if-im-booting-using-uefi – Ciro Santilli OurBigBook.com Sep 07 '15 at 12:36
3 Answers
193
The easiest way is to check to see if /sys/firmware/efi exists. It does not appear if you booted using traditional BIOS.
#!/bin/bash
[ -d /sys/firmware/efi ] && echo UEFI || echo BIOS
Colin Ian King
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Tested on QEMU 2.0.0, OVFM and Ubuntu 14.04: https://github.com/cirosantilli/runlinux/tree/9f03d08838705082c0e316dcff6a199bd4edac0c – Ciro Santilli OurBigBook.com Sep 07 '15 at 13:36
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5nitpick, that expression is POSIX so should work in a variety of shells, not just
bash– iruvar Nov 30 '19 at 19:45 -
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Deprecated
The answer below is a method that may not always work.
Instead use Colin's answer based on/sys/firmware/efi.
It's very easy to tell if a system was booted in EFI (or not, in which case it must be BIOS):
Just use dmesg | grep "EFI v"
This will return a line like this, if the system was booted off of EFI:
[ 0.000000] EFI v2.00 by American Megatrends
Or return nothing if it was not, in which case it was booted off of BIOS
Example of bash script usage based on grep's exit code:
...
dmesg | grep -q "EFI v" # -q tell grep to output nothing
if [ $? -eq 0 ] # check exit code; if 0 EFI, else BIOS
then
echo "You are using EFI boot."
else
echo "You are using BIOS boot"
fi
...
Source: For how to determine if an EFI system is using legacy-BIOS emulation or not, as well as more information on testing for EFI and EFI compatibility, along with the strings for a number of EFI vendors/versions, please see this page from the Ubuntu Developer Summit for Precise.
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2I'd simplify that to
if dmesg | grep -Fq "EFI v"; then .... No point in running the[command in addition, just to test for success/failure.$?is mainly useful for checking for specific errors. – geirha Jul 12 '12 at 10:50 -
3This is brittle, as there is no guarantee that the string searched for is generated by the desired feature. – Thorbjørn Ravn Andersen Jul 13 '12 at 01:28
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@ThorbjørnRavnAndersen: The Ubuntu Developer Summit folks seem to think it's part of the specification...can you provide a source or reference for your contention? – ish Jul 13 '12 at 01:30
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2@izx, any script can happen to write "EFI v" as part of something else. If that happens on a BIOS machine, this would be a false positive. – Thorbjørn Ravn Andersen Jul 13 '12 at 01:37
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2Best not to grep for text in the kernel log, it is subject to change. Best to look at /sys/firmware/efi – Colin Ian King Jul 27 '12 at 18:24
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2I'd like to mention however that this is a great way to get the EFI version! – Alexander Trauzzi Sep 03 '12 at 02:01
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Go figure ...
ls: cannot access '/etc/firmware': No such file or directoryhowever[0.000000] efi: EFI v2.60 by American Megatrends. This is on an Arch. – Vorac Sep 28 '20 at 01:21 -
1@Vorac, I believe the accepted approach is to look in
/sys/firmware/efi, not/etc/firmware. Did you check to see if the former exists? – tgm1024--Monica was mistreated Feb 12 '21 at 14:58
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Python code to check if system is booted with UEFI or ROM BIOS:
import os,sys
def main():
if(os.path.exists("/sys/firmware/efi")):
print"\n\n System is booted with uefi!"
else:
print"\n\n System is booted with rom bios"
main()
sys.exit(0)
