You can use
Snap on Middle to divide the line or add Point entities on the line.
Default is 1 middle point, thus you can snap at 1/2".
When you divide the line you can then divide the two 1/2" lines again in the middle and so on.
Or you change the number of middle points for the snap tool. On the Tool Option Bat (on the top) is a input box where you can change 1 middle point to 7 middle points, then the snap tool will snap on the line every 1/8".
Or you start with a 1/8" line and use the Modify->Copy/Move tool to create 7 copies with 1/8" distance, this will also result in a 1" line.
See:
https://librecad.readthedocs.io/en/latest/ref/snaps.html?highlight=snap#snappinghttps://librecad.readthedocs.io/en/latest/ref/toolbars.html?highlight=tool%20option%20bar#tool-optionshttps://librecad.readthedocs.io/en/latest/ref/tools.html?highlight=copy%2Fmove#modify
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