Custom Mint-19.2 with Linuxcnc

I think someone asked about updating the Linuxcnc version of this ISO ftom 2.8 to 2.9 by compiling from source. That is not required, it can easily be done by:
Open synaptics, search for Linixcnc, mark for complete removal, aplly, exit.
Go to:
Buildbot.linuxcnc.org/~buildmaster/dists/
Click on streatch, master, 64bit, near the end are latest DEB's with linuxcnc-userpace in their name, chose the largest number in the name, download, open with Gdebi, install.
That is it, it takes about 3 to 5 mimutes.

@porche,
The ISO images here and the ones you used at the beginning from the other topic are all custom ISO's with kernels and Linuxcnc installed, that is why i asked earlier why are you trying to compile Linuxcnc on a system with Linuxcnc already installed ?
Now i went back and read your posts, you were trying to install Linuxcnc version 2.9 on an RTAI kernel version, i can not recall that there is a 2.9 version for RTAI at all, just checked there is no such thing, although i might have missed it.
Again, ISO's on this thread and the other thread that is now superseded by this one are fully installed and functional even as Live booted from USB, meaning you can configure and run the machine from the USB or after installing it to hard drive, without installing any additional stuff.