Fortigate Base Operating system?

[duahimanshu]

Hello Expert, I understand this might seem like a kid's question, but what is the underlining operating system of FortiGate?  is it Linux or BSD or something else.

[Toshi_Esumi]

See below:
https://community.fortinet.com/t5/Support-Forum/What-version-of-linux-is-the-fortios-running/td-p/94...

And below is from one of our 40Fs.

FortiGate-40F # fnsysctl cat /proc/version
Linux version 3.10.15 (root@build) (gcc version 10.3.0 (GCC) ) #2 SMP Tue Jun 6 16:11:35 UTC 2023

Toshi