Heat map from multiple files with cat, awk or sed (bash) - bash

Question

I'm dealing with multiple files and I want to plot a heat map every ::121::600 using 3:25:43 from those files.
Is there a way to combine all files on the fly to get a heat map with commands like:
set dgrid3d
splot '< cat data1.csv data2.csv data3.csv data4.csv' every ::121::600 using 3:25:43 w pm3d
I tried this but It seems that only the data from data1.csv shows up in the plot. Am I doing something wrong with ' or , ? Is awk, or sed an option?
i know the option set table but I would prefer a clean bash command option to directly make this on the fly.
Is there a good resource to look up all the unix commands with some gnuplot demos?
Thanks so far for the response:
so the 'are for the plot command: e.g. plot 'data1.csv' using 1:2 w l would print row 1 against row 2 from the data1 file with lines. that's why I used to 'in the command. I found this Site where hey explain some bash commands for gunplot but I still haven't found what I'm looking for
Thank you for the great respones and help regarding my problem:
This worked:
plot '< for i in data1.csv data2.csv data3.csv data4.csv; do cat "$i"; echo; done' every ::121::600 using 3:25:43 w pm3d
Worth mentioning that I do had to ad the "around the $ijust as vagoberto proposed
and this worked the same way:
plot '< awk "FNR==1{print \"\"}1" data1.csv data2.csv data3.csv data4.csv' every ::121::600 using 3:25:43 w pm3d
both worked on my Mac OSX Terminal environment, and on Wind 7 with gnuWin32 Package installed.

Answer 1

The every ::121::600 command is telling gnuplot to take the data from lines 121 to 600 (counting from 0) on every block, and not on every files. You need to pre-process the data to create blocks (put a single line between each data).
Consider the following two data files:
#data1.dat #data2.dat
1 2 1.5 2.5 # line 0
3 4 3.5 4.5 # line 1
5 6 5.5 6.5 # line 2
and try to plot with every ::2::2 (i.e. plot only line 2).
The following instruction creates a single block, so gnuplot will plot only the point (5,6):
cat data1.dat data2.dat
1 2
3 4
5 6
1.5 2.5
3.5 4.5
5.5 6.5
The following instruction will create a block for each datafile, so that gnuplot will plot the points (5,6) and (5.5,6.5):
for i in data*.dat; do cat $i; echo; done
1 2
3 4
5 6
1.5 2.5
3.5 4.5
5.5 6.5
You will get a similar result by using awk 'FNR==1{print ""}1' data*.dat.
In summary, the following should work:
plot '< for i in data*.dat; do cat $i; echo; done' every ::2::2 using 1:2
# or
plot '< awk "FNR==1{print \"\"}1" data*.dat' every ::2::2 using 1:2