If you add the following control section to your input file adder-mos.cir, you may call

ngspice adder-mos.cir

from the command line and see ngspice starting, simulating and then plotting immediately.

Control section:

*  ADDER - 4 BIT ALL-NAND-GATE BINARY ADDER 
.control 
unset askquit 
save vcc#branch  
run 
plot vcc#branch  
rusage all 
.endc

Any suitable command listed in Chapt. 17.5 may be added to the control section, as well as control structures described in Chapt. 17.6. Batch-like behavior may be obtained by changing the control section to

Control section with batch-like behavior:

*  ADDER - 4 BIT ALL-NAND-GATE BINARY ADDER 
.control 
unset askquit 
save vcc#branch  
run 
write adder.raw vcc#branch  
quit 
.endc

If you put this control section into a file, say adder-start.sp, you may just add the line

.include adder-start.sp

to your input file adder-mos.cir to obtain the batch-like behavior. In the following example the line .tran ... from the input file is overridden by the tran command given in the control section.

Control section overriding the .tran command:

*  ADDER - 4 BIT ALL-NAND-GATE BINARY ADDER 
.control 
unset askquit 
save vcc#branch  
tran 1n 500n 
plot vcc#branch  
rusage all 
.endc

The commands within the .control section are executed in the order they are listed and only after the circuit has been read in and parsed. If you want to have a command being executed before circuit parsing, you may use the prefix pre_ (17.5.49) to the command.

A warning is due however: If your circuit file contains such a control section (.control ... .endc), you should not start ngspice in batch mode (with -b as parameter). The outcome may be unpredictable!