Please HELP, SD card read to send gcode to another arduino

Theres examples of data logging to sd card, i cant find any thats read the sdcard.
I would like to use it to read Gcode stored in SDcard to feed to another arduino with grbl1.1 using the TX RX pin. My DIY glue application XY machine works fine now presently with 2 sizes of wooden board by selector switch to select the 2 sets of Gcodes which are fixed coded in another control arduino using XOD data index(NCsteps) haha works. Only i have to change the pogram if size do differ next time. anyone know how to read the SDcard text files please HELP.
Thank you XODERS.