Is that

/var/www/moodledata/stack/plots/

Here some of the output from my healthcheck and I was curious about the line that reads

URL_BASE:"!ploturl!",

Which seems a little odd

STACK_SETUP(ex):=block(

MAXIMA_VERSION_NUM_EXPECTED:38,

MAXIMA_PLATFORM:"server",

maxima_tempdir:"/var/www/moodledata/stack/tmp/",

IMAGE_DIR:"/var/www/moodledata/stack/plots/",

PLOT_TERMINAL:"png",

PLOT_TERM_OPT:"large transparent size 450,300",

DEL_CMD:"rm",

GNUPLOT_CMD:"/usr/bin/gnuplot",

MAXIMA_VERSION_EXPECTED:"5.38.0",

URL_BASE:"!ploturl!",

/* Define units available in STACK. */

stack_unit_si_prefix_code:[y, z, a, f, p, n, u, m, c, d, da, h, k, M, G, T, P, E, Z, Y],

stack_unit_si_prefix_multiplier:[10^-24, 10^-21, 10^-18, 10^-15, 10^-12, 10^-9, 10^-6, 10^-3, 10^-2, 10^-1, 10, 10^2, 10^3, 10^6, 10^9, 10^12, 10^15, 10^18, 10^21, 10^24],

stack_unit_si_prefix_tex:["\\mathrm{y}", "\\mathrm{z}", "\\mathrm{a}", "\\mathrm{f}", "\\mathrm{p}", "\\mathrm{n}", "\\mu ", "\\mathrm{m}", "\\mathrm{c}", "\\mathrm{d}", "\\mathrm{da}", "\\mathrm{h}", "\\mathrm{k}", "\\mathrm{M}", "\\mathrm{G}", "\\mathrm{T}", "\\mathrm{P}", "\\mathrm{E}", "\\mathrm{Z}", "\\mathrm{Y}"],

stack_unit_si_unit_code:[m, l, L, g, s, h, Hz, Bq, cd, N, Pa, cal, Cal, Btu, eV, J, W, A, ohm, C, V, F, S, Wb, T, H, Gy, rem, Sv, lx, mol, M, kat, rad],

stack_unit_si_unit_conversions:[m, m^3/1000, m^3/1000, kg/1000, s, s*3600, 1/s, 1/s, cd, (kg*m)/s^2, kg/(m*s^2), 4.2*J, 4200*J, 1055*J, 1.602177e-19*J, (kg*m^2)/s^2, (kg*m^2)/s^3, A, (kg*m^2)/(s^3*A^2), s*A, (kg*m^2)/(s^3*A), (s^4*A^2)/(kg*m^2), (s^3*A^2)/(kg*m^2), (kg*m^2)/(s^2*A), kg/(s^2*A), (kg*m^2)/(s^2*A^2), m^2/s^2, 0.01*Sv, m^2/s^2, cd/m^2, mol, mol/(m^3/1000), mol/s, rad],

stack_unit_si_unit_tex:["\\mathrm{m}", "\\mathrm{l}", "\\mathrm{L}", "\\mathrm{g}", "\\mathrm{s}", "\\mathrm{h}", "\\mathrm{Hz}", "\\mathrm{Bq}", "\\mathrm{cd}", "\\mathrm{N}", "\\mathrm{Pa}", "\\mathrm{cal}", "\\mathrm{cal}", "\\mathrm{Btu}", "\\mathrm{eV}", "\\mathrm{J}", "\\mathrm{W}", "\\mathrm{A}", "\\Omega", "\\mathrm{C}", "\\mathrm{V}", "\\mathrm{F}", "\\mathrm{S}", "\\mathrm{Wb}", "\\mathrm{T}", "\\mathrm{H}", "\\mathrm{Gy}", "\\mathrm{rem}", "\\mathrm{Sv}", "\\mathrm{lx}", "\\mathrm{mol}", "\\mathrm{M}", "\\mathrm{kat}", "\\mathrm{rad}"],

stack_unit_other_unit_code:[min, amu, u, mmHg, bar, cc, gal, mbar, atm, Torr, rev, deg, rpm, K, day, year],

stack_unit_other_unit_conversions:[s*60, amu, amu, 133.322387415*Pa, 10^5*Pa, m^3*10^(-6), 3.785*l, 10^2*Pa, 101325*Pa, 101325/760*Pa, 2*pi*rad, pi*rad/180, pi*rad/(30*s), K, 86400*s, 3.156e7*s],

stack_unit_other_unit_tex:["\\mathrm{min}", "\\mathrm{amu}", "\\mathrm{u}", "\\mathrm{mmHg}", "\\mathrm{bar}", "\\mathrm{cc}", "\\mathrm{gal}", "\\mathrm{mbar}", "\\mathrm{atm}", "\\mathrm{Torr}", "\\mathrm{rev}", "\\mathrm{{}^{o}}", "\\mathrm{rpm}", "\\mathrm{K}", "\\mathrm{day}", "\\mathrm{year}"],

true)$

/* Load the main libraries. */

load("stackmaxima.mac")$

load("stats")$

load("distrib")$

load("descriptive")$

print(sconcat("[ STACK-Maxima started, library version ", stackmaximaversion, " ]"))$