@User Everything worked well. But I am trying to simulate the Inverter circuit with ngspice "batch" mode selected. Initially, it took less time more or less 45 seconds to pop out the window indicating the raw file created in the location ".xschem/simulations". But now I have pressed the button "Simulate" in xschem next to "netlist", it has been red for last 30 minutes but it is not coming to the end. Before simulating the circuit, I had deleted the old .out, .spice, .raw files. but now it is taking too long for simulating the inverter circuit using ngspice batch mode selected. I selected batch mode because I wanted to check whether the gaw software for the waveform working fine or not. Please suggest what should be done?