In the documentation, I Gnuplot / Expressions / Summation, we can see that variable MAXCOL can be used :
plot ’data’ using 1 : (sum [col=2:MAXCOL] column(col))
What I would like is to be able to use syntax like
plot 'myfile' using MAXCOL:xtic(1) with boxes
Thus, I do not have to hard code the value of last column number.