Octave: how to read a data file, plot and save graph?

Octave/MatLab : how to read a data file, plot and save graph?
Octave/MatLab : how to read a data file?
Octave : how to plot graph?
Octave :how to save graph?

h_data = load("h_hist.txt");
plot ( h_data(:, 1), h_data(:,2) )
print -djpg h_hist.jpg

v_data1 = load("v_hist1.txt")
plot (v_data1(:, 1), v_data1(:,2) )
print -dpdf v_hist1.pdf

v_data2 = load("v_hist2.txt")
plot ( v_data2(:,1), v_data2(:, 2) )
print -dpdf v_hist2.pdf
print -djpg v_hist2.jpg