Gnuplot may be executed in either batch or interactive modes, and the two may even be mixed together on many systems.
Any command-line arguments are assumed to be either program options (first character is -) or names of files containing gnuplot commands. The option -e "command" may be used to force execution of a gnuplot command. Each file or command string will be executed in the order specified. The special filename "-" is indicates that commands are to be read from stdin. Gnuplot exits after the last file is processed. If no load files and no command strings are specified, gnuplot accepts interactive input from stdin.
To launch an interactive session:
To launch a batch session using two command files "input1" and "input2":
gnuplot input1 input2
To launch an interactive session after an initialization file "header" and followed by another command file "trailer":
gnuplot header - trailer
To give gnuplot commands directly in the command line, using the "-persist" option so that the plot remains on the screen afterwards:
gnuplot -persist -e "set title 'Sine curve'; plot sin(x)"
To set user-defined variables a and s prior to executing commands from a file:
gnuplot -e "a=2; s='file.png'" input.gpl