Individually for all scale sets, it is working fine but when i use alter command to show curves for different scale sets in one graph, it is giving error like this. I'm getting output for only one set which is given at the beginning.

like i guess you used capital w in .control block,is that correct?

Yes I used capital... But it doesnt change any result right

ok ngspice is not case sensitive? like i am having doubt

no

@Akurathi Radhika: I believe the problem is that "alter" wants to work on the device, not the subcircuit, so that you would want to use

XM2.Msky130_fd_pr__pfet_01v8

instead of

XM2

, for example. It's either that, or else it wants

alter @XM2[w]

. But I think the

@

form is supposed to be equivalent. ngspice syntax is very finicky. . .

No.. I've tried that but still showing same error