Getting started with Linux, LinuxCNC and CNC

I have replced the electronicsand the steppers on my Emco yesterday. Got a slightly better performance than before (mainly due to low voltage power source) bit thats something to work on.

I have few other questions. I used simple china 5axis bob. Got the e stop working properly. My main switch is killing the power to the swittchung supply and the bob.
How can I make linux not to ask me to home it every time I turn the machine off and then on?
How can I make linuxcnc to "turn off" (to dim the power button" when I turn off the main switch?
Because g54 and similar commands wont work when its not homed. And if I turn off the lathe on the main switch, and linuxcnc keeps runing, the position changes I make on it doesnt affect the tool position when I turn the lathe on again.
For instance, if I position the cutter to 0,0 and turn off the lathe, if I move the position in linuxcnc (that is still running) to 10,10, when I turn the machine back on, cutter stays in same position, but it reads 10,10 (and not 0,0 like when I turend it off).
Oh, and one more thing - I dont see the cutter image on preview, when I load the tool with m6 g43 command.
And cancI just copy the tool table fromcthe old setup, I havent made any changes on them physically?
Thanks

sharpshooterser wrote: How can I make linux not to ask me to home it every time I turn the machine off and then on?

See the ini-config docs on NO_FORCE_HOMING
linuxcnc.org/docs/2.7/html/config/ini-config.html#_traj_section

How can I make linuxcnc to "turn off" (to dim the power button" when I turn off the main switch?

You could make the main power also operate a tiny relay that switches a GPIO to drive the pin motion.enable
linuxcnc.org/docs/2.7/html/man/man9/motion.9.html
If your GPIO can handle the main-switch control voltage then you might not need the relay, but you probably need flyback diodes.

Oh, and one more thing - I dont see the cutter image on preview, when I load the tool with m6 g43 command

Does the tool table specify orientation, front angle and back angle.

Thanks Andy - got it on homing, and tool table is all set up.
As for GPIO, I ll have to work on that, but its doable.

solved

Hm, two more questions.
I ll try my best to explain what happens - in several occasions, I have loaded the desired tool (for instance T1) touched off the part for x and z, loaded the desired ngc file, press play and... the coordinates change - what I have set 30 seconds ago as lets say x10 z10 on DRO is now x-45z-128. Darn. Its not a problem if I work on one piece, but it is a problem when it happens when I m in a middle of the run, so I have to re-position everything. Or if (as it did) the carriage hits the tailstock supporting the work piece. What can cause it, and how to cure it?

Second question (I might have asked before) is for subroutines, the taper OD one. Its all good when you work right to left, from smaller od to larger - to chamfer the edge for instance. But what if I need it to do the opposite - working from right to left, normal right hand tool, to cut from larger od to smaller od? Is it possible, or does one have to work a separate subroutine for it?
Thanks fellas

First answer, you have active offsets, so consult the gcode quick reference to cancel all offsets.
Second, i can not help, sorry