/usr/bin/xy-plot is in ncbi-entrez-direct 7.40.20170928+ds-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | #!/bin/sh
# For Mac, please obtain command-line-enabled Plot2x from http://apps.micw.org/apps/plot2/downloads.php
# For Unix or PC/Cygwin, please obtain gnuplot from http://gnuplot.sourceforge.net/download.html
plot2x=
p2x_path=/Applications/Plot2x.app/Contents/MacOS/Plot2x
for pfx in "$HOME" ''
do
  if [ -x "$pfx$p2x_path" ]
  then
    plot2x=$pfx$p2x_path
    break
  fi
done
if [ -n "$plot2x" ]
then
  cat > "$HOME/Desktop/edirect.dat"
  outfile="$HOME/Desktop/edirect.png"
  if [ -n "$*" ]
  then
    outfile="$*"
  fi
  cat > "$HOME/Desktop/edirect.macro" <<EOF
import $HOME/Desktop/edirect.dat 0
savepng $outfile
EOF
  eval "$plot2x -m $HOME/Desktop/edirect.macro -q yes -h yes"
  rm "$HOME/Desktop/edirect.dat"
  rm "$HOME/Desktop/edirect.macro"
elif hash gnuplot 2>/dev/null
then
  cat > "edirect.dat"
  outfile="edirect.png"
  if [ -n "$*" ]
  then
    outfile="$*"
  fi
  gnuplot -e "set terminal png; set output '$outfile'; unset key; plot 'edirect.dat' with lines"
  rm "edirect.dat"
else
  echo "To generate .png output please install either gnuplot or Plot2x" >&2
fi
if [ -f "$outfile" ]
then
  case "`uname -s`" in
    Darwin     ) open "$outfile" ;;
    CYGWIN_NT* ) cygstart "$outfile" ;;
    *          ) xdg-open "$outfile" 2>/dev/null ;;
  esac
fi
 |