@p >Sure seems to support the standard Unix kernel interfaces and run Unix software.
>Look at the photo.
>It is GNU bash running GNU Compiler Collection to compile and link the software against glibc.
Facepalm into the nether realm.

>cal instead of gcal
Sad!

>uname
name --help;
Usage: uname [OPTION]...
Print certain system information. ***With no OPTION, same as -s****.
-s, --kernel-name print the kernel name
...
-o, --operating-system print the operating system
--help display this help and exit
--version output version information and exit

uname -o;
GNU/Linux

uname --version
uname (GNU coreutils) 9.5
Packaged by Gentoo (9.5 (p0))
Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by David MacKenzie.

>When did GPLv2 turn "proprietary"?
Linux was proprietary software in 1991, but was released under the GPLv2-ambigious in 1996.

It only took until 1996 before the first proprietary program was added to Linux and Linux became proprietary software again.

One of many examples of proprietary software added to Linux is this; https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/platforms/8xx/micropatch.c (the binary form is array encoded and there is no source code).

When it comes to the license of Linux, generally it is only enforced *against* freedom, rather than in support of it.