does linuxcnc have joint interpolation inside?

F-Error is a different thing.

And if you tried it "a long time ago" then that might well have been before the Joints-Axes merge?

This is one of your issues:
github.com/LinuxCNC/linuxcnc/issues/97

I dont know any way of controlling joints from gcode...

Sorry, i think i misunderstand the way point to point planning trajectory work. I think the way should be:
Get Cartesian position ---> inverse kinematic --->interpolation--> motion. ( skip G1, G2,...)

[strike]There is a function name "teleop_vector" in python interface:
[/strike] linuxcnc.org/docs/2.6/html/common/python..._linuxcnc_command_tt

[strike]I wonder how it work but i cant find this function in:
[/strike] github.com/LinuxCNC/linuxcnc/blob/master...s/emcmodule.cc#L1296

[strike]was it removed in master-branch?
[/strike]This function is not relative