example usage

gnuplot/README.md

@@ -3,6 +3,12 @@
 
 
 
+    usage:
+      gnuplot line.gp                       run line.gp script
+      gnuplot -p line.gp                    run script and kepp figure open
+      gnuplot -e "file='data.dat'; column1=1; column2=2; format=''; out=''" line.gp
+                                            run script with altered variables
+
 [line.gp](./line.gp)
 
 ![img](./line.png)