Shell front end that enables you to use Gnuplot from a shell pipeline

example

#!/bin/bash
set -o errexit
set -o nounset

function data() {
  # f(x) = x^2 + noise(500)
  # g(x) = x^2 + noise(2500)
  for i in {1..100}; do
    fx=$((i*i + $RANDOM%1000 - 500))
    gx=$((i*i + $RANDOM%5000 - 2500))
    echo $i, $fx, $gx
  done
}

# Normal plot x, f(x)
data | plot using 1:2

# Connect the points
data | plot using 1:2 with lines

# Plot 2 data series on the same graph (same y-axis)
data | plot using 1:2 with lines, using 1:3 with points

# Label the plot and series
data | plot --title "foo vs. bar" using 1:2 with lines title "'foo'", using 1:3 with points title "'bar'"

# Save the output to a file
data | plot --output png --title "foo vs. bar" using 1:2 with lines title "'foo'", using 1:3 with points title "'bar'" > foo_vs_bar.png

plot

#!/bin/bash
set -o errexit
set -o nounset

function main() {
  local data=$(mktemp "data.XXXXXX")
  local script=$(mktemp "script.XXXXXX")

  # Make sure we always cleanup...
  trap "{ rm -f '${data}' '${script}' >/dev/null 2>&1; }" EXIT

  # Read the data from standard input and save it...
  cat - > "${data}"

  # Parse the command line arguments into a GNU Plot script.  The arguments that
  # start with -- get translated to set statements.  Anything else gets emitted
  # as-is to the script.
  while [[ $# -gt 0 ]]; do
    case "${1}" in
      --*) echo "set ${1:2} '${2}'" >> "${script}"; shift;;
      --)  shift; break;;
      *)   break;;
    esac

    shift
  done

  # Build the plot command from the remaining arguments.  Anytime we encounter
  # the word using, we need to prepend it with the data filename.
  echo -n "plot " >> "${script}"

  while [[ $# -gt 0 ]]; do
    case "${1}" in
      using) echo -n "'${data}' using " >> "${script}";;
      *)     echo -n "${1} " >> "${script}";;
    esac

    shift
  done

  # Plot
  gnuplot --persist "${script}"
}

main "$@"