Difficulty building RTAI linuxcnc from source

The huge list is everyting that is needed to build a LinuxCNC package including documentation). You might as well do it, even if some of them are not needed, it only takes about 5 minutes.

One of the dependencies in the list is probably linux-headers-xxx-rtai, and that will solve the version.h problem (and many others)

I did a video about how to build Linuxcnc and how to sort out the dependencies.

I did sudo apt-get install on each of the unmet dependencies until there were none left. Wow! ... didn't think it would work ...

OK. I went to linuxcnc-dev\src and did ./autogen.sh then did ./configure
but (groan) configure returned the same error as before

robert@debian:~/linuxcnc-dev/src$ ./configure
checking for c++... c++
checking whether the C++ compiler works... yes
checking for C++ compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C++ compiler... yes
checking whether c++ accepts -g... yes
checking for a BSD-compatible install... /usr/bin/install -c
checking whether c++ supports C++17 features with -std=gnu++17... yes
checking build toplevel... /home/robert/linuxcnc-dev
checking installation prefix... run in place
checking for grep... /usr/bin/grep
checking for egrep... /usr/bin/egrep
checking for pkg-config... /usr/bin/pkg-config
checking for gcc... gcc
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking how to run the C preprocessor... gcc -E
checking for grep that handles long lines and -e... (cached) /usr/bin/grep
checking for egrep... (cached) /usr/bin/egrep
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking rpc/rpc.h usability... yes
checking rpc/rpc.h presence... yes
checking for rpc/rpc.h... yes
checking for rtai-config... /usr/realtime-4.19.195-rtai-amd64/bin/rtai-config
checking for xeno-config... none
checking for realtime API(s) to use... /usr/realtime-4.19.195-rtai-amd64/bin/rtai-config
checking for location of kernel headers... using value from RTS: /usr/src/linux-headers-4.19.195-rtai-amd64
checking for cc version... found gcc in rtai-config
checking whether we are using the GNU C compiler... (cached) yes
checking whether gcc accepts -g... (cached) yes
checking for gcc option to accept ISO C89... (cached) none needed
checking how to run the C preprocessor... gcc -E
checking for usability of linux/hidraw.h... yes
checking for usability of rpc/rpc.h... yes
checking for libmodbus3... yes - version 3.1.4
checking for libusb-1.0... yes
checking for kernel version string... gcc: error: /usr/src/linux-headers-4.19.195-rtai-amd64/include/linux/version.h: No such file or directory
gcc: fatal error: no input files
compilation terminated.
configure: error: Kernel version string not found
robert@debian:~/linuxcnc-dev/src$

The only theory I have is that the code is set up for a non-realtime build, the user space build. When I was following directions for taking care of dependencies, the first instruction was to run ./debian/configure. When I did that, the return was "successfully configured for uspace-Debian".
Maybe if the configure files think I'm not wanting a realtime build, they don't take care of the realtime headers. Just a guess.

That could be it, though depending on the LinuxCNC version you are using the debian folder might not currently know how to make RTAI debs at all.
(I am trying to fix that)
It isn't a huge problem, it just means that it may have missed a dependency.

Try
sudo apt-get install linux-headers-4.19.195-rtai-amd64
and
sudo apt-get install linux-libc-dev

I don't know if either of those will work, but both appear to provide a version.h

Hi -
Thank you very much. Sometimes I get so wrapped up in this process I forget to say that.
I ran your two sudo apt-get installs, then re-ran configure. Configure had a little problem at the end, having to do with licensing. It suggested an option to append to the ./configure call, which I implemented. Then configure ran through to the end! !!
It put up a congratulatory summary box surrounded by asterisks, told me to run make.
I ran make. The computer chugged away for what felt like several minutes, putting up all kinds of verbiage. Then it stumbled at the end, saying a for loop could only be handled correctly by C99 or C11. It suggested a -std=c99 option, so I did "make -std=c99" and it busted me immediately with multiple invalid option errors. I'm attaching the end of the make output.
One thing that occurred to me: If make had been successful, would there have been a linuxcnc executable someplace? Where? Would I just do ./linuxcnc to run it?

LD [M] /home/robert/linuxcnc-dev/src/tof.o
CC [M] /home/robert/linuxcnc-dev/src/objects/hal/components/match8.o
LD [M] /home/robert/linuxcnc-dev/src/match8.o
CC [M] /home/robert/linuxcnc-dev/src/objects/hal/components/timedelay.o
LD [M] /home/robert/linuxcnc-dev/src/timedelay.o
CC [M] /home/robert/linuxcnc-dev/src/objects/hal/components/limit_axis.o
hal/components/limit_axis.comp: In function ‘_’:
hal/components/limit_axis.comp:67:3: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode
hal/components/limit_axis.comp:67:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
make[2]: *** [scripts/Makefile.build:304: /home/robert/linuxcnc-dev/src/objects/hal/components/limit_axis.o] Error 1
make[1]: *** [Makefile:1547: _module_/home/robert/linuxcnc-dev/src] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-4.19.195-rtai-amd64'
make: *** [Makefile:547: modules] Error 2
robert@debian:~/linuxcnc-dev/src$

I was struggling with that "C99" thing myself last week. Never did get to the bottom of it.

I just deleted limit_axis.comp ....
(And another one, I forgot which, but it will become evident)

Nearly all of linuxCNC is C89 compliant, just a couple of new comps use the C99 loop declaration, and those are found by name, so just deleting them bypasses the problem.