gnuplot : plotting data from multiple input files in a single graph

replot

This is another way to get multiple plots at once:

plot file1.data
replot file2.data

You may find that gnuplot's for loops are useful in this case, if you adjust your filenames or graph titles appropriately.

e.g.

filenames = "first second third fourth fifth"
plot for [file in filenames] file."dat" using 1:2 with lines

and

filename(n) = sprintf("file_%d", n)
plot for [i=1:10] filename(i) using 1:2 with lines

You're so close!

Change

plot "print_1012720" using 1:2 title "Flow 1", \
plot "print_1058167" using 1:2 title "Flow 2", \
plot "print_193548"  using 1:2 title "Flow 3", \ 
plot "print_401125"  using 1:2 title "Flow 4", \
plot "print_401275"  using 1:2 title "Flow 5", \
plot "print_401276"  using 1:2 title "Flow 6"

to

plot "print_1012720" using 1:2 title "Flow 1", \
     "print_1058167" using 1:2 title "Flow 2", \
     "print_193548"  using 1:2 title "Flow 3", \ 
     "print_401125"  using 1:2 title "Flow 4", \
     "print_401275"  using 1:2 title "Flow 5", \
     "print_401276"  using 1:2 title "Flow 6"

The error arises because gnuplot is trying to interpret the word "plot" as the filename to plot, but you haven't assigned any strings to a variable named "plot" (which is good – that would be super confusing).