The command lines described in this chapter are specifying analyses and outputs within the circuit description file. They start with a `.' (dot commands). Specifying analyses and plots (or tables) in the input file with dot commands is used with batch runs. Batch mode is entered when either the -b option is given upon starting ngspice

ngspice -b -r rawfile.raw circuitfile.cir

or when the default input source is redirected from a file (see also Chapt. 16.4.1).

ngspice < circuitfile.cir

In batch mode, the analyses specified by the control lines in the input file (e.g. .ac, .tran, etc.) are immediately executed. If the -r rawfile option is given then all data generated is written to a ngspice rawfile. The rawfile may later be read by the interactive mode of ngspice using the load command (see 17.5.40). In this case, the .save line (see 15.6) may be used to record the value of internal device variables (see Appendix, Chapt. 31).

If a rawfile is not specified, then output plots (in `line-printer' form) and tables can be printed according to the .print, .plot, and .four control lines, described in Chapt. 15.6.

If ngspice is started in interactive mode (see Chapt. 16.4.2), like

ngspice circuitfile.cir

and no control section (.control ... .endc, see 16.4.3) is provided in the circuit file, the dot commands are not executed immediately, but are waiting for manually receiving the command run.