Following displays 4 curves, as expected:
plot "a.csv" using 1:2 lw 4 with lines, \
'' using 1:3 lw 4 with lines, \
"b.csv" using 1:2 lw 4 with lines, \
'' using 1:3 lw 4 with lines
However, the following displays only 3 curves:
plot for [flnm in "a.csv b.csv"] \
flnm using 1:2 lw 4 with lines, \
'' using 1:3 lw 4 with lines
What's the error in the "plot for" command?
The "for [xx=yy:zz]" only applies to the plot clause it introduces. You would need something like this
plot for [flnm in "a.csv b.csv"] flnm using 1:2 lw 4 with lines, \
for [flnm in "a.csv b.csv"] flnm using 1:3 lw 4 with lines
or like this
plot for [flnm in "a.csv b.csv"] for [col=2:3] \
flnam using 1:col lw 4 with lines