is there some easier way to find setup and hold time in ngspice rather than just continuously moving data signal with respect to clock signal till we get invalid output,

Not that I can think of. For efficiency, though, you could set up a big array of devices, each with a different delay in the data signal, so you can quickly hone in on the result.

yeah sir that seems good ,but in hspice i found there is bisection method to find detup time through optimisation,is there method like that ingspice

@Varun Majji you can definitely set up a bisection algorithm with ngspice by using a ngspice .control script. However writing ngspice scripts requires considerable time (unless you are already skilled in its script language, i tend to do the same mistakes over and over again) to get it working so i don't know if it is worth doing.

Hmm, would it make sense to have a bisection algorithm as a dedicated simulation type with its own command and simple parameters?

yeah that would be great