gnuplot-free

#!/bin/bash


points=30
interval=1


####################

set -o pipefail
spool=$(mktemp -d /tmp/free_plot.XXXXX)
cd "$spool"

cleanup() {
	rm -rf --one-file-system "$spool"
	jobs=$(jobs -rp)
	[[ -n "$jobs" ]] && {
		kill $(jobs -rp) 2>/dev/null
		wait $(jobs -rp) 2>/dev/null
	}
	pkill -g 0
}
trap cleanup EXIT

####################

free -m -s $interval |
	awk '
		BEGIN {
			# exports="available"
			exports="total used free buff/cache available"
			agg="free_plot.datz"
			dst="free_plot.dat" }
		$1=="total" {
			for (n=1;n<=NF;n++)
				if (index(exports,$n)) headers[n+1]=$n }
		$1=="Mem:" {
			first=1
			printf "" >dst
			for (n in headers) {
				if (!first) {
					printf " " >>agg
					printf " " >>dst }
				printf "%d", $n >>agg
				printf "%s", headers[n] >>dst
				first=0 }
			printf "\n" >>agg
			printf "\n" >>dst
			fflush(agg)
			close(dst)
			system("tail -n '$points' " agg " >>" dst) }' &

####################

cat >free_plot.gnu <<EOF
src='free_plot.dat'
y0=100; y1=2000;
set xrange [1:30]
set yrange [y0:y1]

# --------------------
set terminal unknown
stats src using 5 name 'y' nooutput

is_NaN(v) = v+0 != v
y_first=0
grab_first_y(y) = y_first = y_first!=0 && !is_NaN(y_first) ? y_first : y
grab_last_y(y) = y_last = y

plot src u (grab_first_y(grab_last_y(\$5)))
x_first=GPVAL_DATA_X_MIN
x_last=GPVAL_DATA_X_MAX

# --------------------
set label 1 sprintf('first: %d', y_first) at x_first,y_first left offset 5,-1
set label 2 sprintf('last: %d', y_last) at x_last,y_last right offset 0,1
set label 3 sprintf('min: %d', y_min) at 0,y0-(y1-y0)/15 left offset 5,0
set label 4 sprintf('max: %d', y_max) at 0,y0-(y1-y0)/15 left offset 5,1

# --------------------
set terminal x11 nopersist noraise enhanced
set xlabel 'n'
set ylabel 'megs'

set style line 1 lt 1 lw 1 pt 2 pi -1 ps 1.5
set pointintervalbox 2

plot\
	src u 5 w linespoints linestyle 1 t columnheader,\
	src u 1 w lines title columnheader,\
	src u 2 w lines title columnheader,\
	src u 3 w lines title columnheader,\
	src u 4 w lines title columnheader,\

# --------------------
pause 1
reread
EOF
gnuplot free_plot.gnu 2>&1 |
	grep -vE -e '^[[:space:]]*$'\
		-e '^WARNING: Plotting with an '\''unknown'\'' terminal\.$'\
		-e '^No output will be generated\.'\
		-e 'All points out of range' &

####################

sleep 1 # gives awk time to create a file
tail -f free_plot.datz