Gnuplot wrapper with better defaults for quick line charts

qp.sh

#!/usr/bin/env bash
#
# QuickPlot - Gnuplot wrapper with better defaults for quick line charts
#
# Usage:
#     qp < file.dat
#     qp file-1.dat file-2.dat ...
#
# File formats:
#     - <x>
#     - <x> <y>

COMMANDS='
line_width = 1.25;
set style line  1 linetype 1 linecolor rgb "#0099cc" linewidth line_width;
set style line  2 linetype 1 linecolor rgb "#9933cc" linewidth line_width;
set style line  3 linetype 1 linecolor rgb "#669900" linewidth line_width;
set style line  4 linetype 1 linecolor rgb "#ff8800" linewidth line_width;
set style line  5 linetype 1 linecolor rgb "#cc0000" linewidth line_width;
set style line  6 linetype 2 linecolor rgb "#0099cc" linewidth line_width;
set style line  7 linetype 2 linecolor rgb "#9933cc" linewidth line_width;
set style line  8 linetype 2 linecolor rgb "#669900" linewidth line_width;
set style line  9 linetype 2 linecolor rgb "#ff8800" linewidth line_width;
set style line 10 linetype 2 linecolor rgb "#cc0000" linewidth line_width;
set style line 11 linetype 3 linecolor rgb "#0099cc" linewidth line_width;
set style line 12 linetype 3 linecolor rgb "#9933cc" linewidth line_width;
set style line 13 linetype 3 linecolor rgb "#669900" linewidth line_width;
set style line 14 linetype 3 linecolor rgb "#ff8800" linewidth line_width;
set style line 15 linetype 3 linecolor rgb "#cc0000" linewidth line_width;
set style line 16 linetype 4 linecolor rgb "#0099cc" linewidth line_width;
set style line 17 linetype 4 linecolor rgb "#9933cc" linewidth line_width;
set style line 18 linetype 4 linecolor rgb "#669900" linewidth line_width;
set style line 19 linetype 4 linecolor rgb "#ff8800" linewidth line_width;
set style line 20 linetype 4 linecolor rgb "#cc0000" linewidth line_width;
set style line 21 linetype 5 linecolor rgb "#0099cc" linewidth line_width;
set style line 22 linetype 5 linecolor rgb "#9933cc" linewidth line_width;
set style line 23 linetype 5 linecolor rgb "#669900" linewidth line_width;
set style line 24 linetype 5 linecolor rgb "#ff8800" linewidth line_width;
set style line 25 linetype 5 linecolor rgb "#cc0000" linewidth line_width;
set style increment user;
set termoption dash;
set grid;
plot'

if [ -t 0 ]; then
    # not piped input
    for FILE in "$@"; do
        COMMANDS="${COMMANDS} \"$FILE\" with lines,"
    done
else
    # piped input
    COMMANDS="${COMMANDS} \"-\" with lines title \"$1\""
fi

gnuplot -p -e "$COMMANDS"