tikzlibrary: external file names with spaces issue

Question

Hello there

Currently trying to implement tikz's external library to a file named stack q.tex

MWE:

\newcommand\subfilename{"./stack q.tex"}
\documentclass{article}
% pgfplots
\usepackage{pgfplots}
% uncommenting generates error
\usetikzlibrary{external}
% External lib
\tikzexternalize[
    up to date check={simple},
    prefix=./.build/figures/
] % turn externalization on/off
\tikzsetfigurename{figure_\arabic{part}.} % set figure names
% Using tikzset generates error
\tikzset{%
    external/system call={%
        lualatex \tikzexternalcheckshellescape
        --halt-on-error
        --shell-escape
        --interaction=batchmode
        --jobname "\image" \subfilename
    }
}
\pgfplotsset{
    compat  = newest,
    width   = 10cm,    % width
    height  =  7cm,    % height
    samples = 10,
}
\begin{document}
% \tikzsetfigurename{figure_\arabic{part}.} % set figure names
\begin{tikzpicture}
    \begin{axis}[hide axis]
    \addplot3 [
        % Aparence
        surf,
        opacity=0.5,
        fill opacity= 1,
        faceted color = white,
        shader=faceted interp,
        % Scope
        data cs = cart, % cart/polar/polarrad
        % Variable
        domain   = -1:1,
        domain y = -1:1,
    ]{
        x^2-y^2
    };

\end{axis}

\end{tikzpicture}
\begin{tikzpicture}
    \begin{axis}[hide axis]
    \addplot3 [
        % Aparence
        surf,
        opacity=0.5,
        fill opacity= 1,
        faceted color = white,
        shader=faceted interp,
        % Scope
        data cs = cart, % cart/polar/polarrad
        % Variable
        variable   = u,
        variable y = v,
        domain   = 0:360,
        domain y = -180:0,
    ]
    (
        {cos(u)*sin(v)}, 
        {sin(u)*sin(v)}, 
        {cos(v)}
    );

\end{axis}

\end{tikzpicture}
\end{document}

The compilation never completes, its stuck in the creation of figure_0.0.aux with the following message being display in the terminal:

This is LuaHBTeX, Version 1.13.2 (TeX Live 2021) 
 system commands enabled.
tput: No value for $TERM and no -T specified

Answer 1

Even when space is not a prohibited character in filenames, the experience of several commenters recommends staying on the safe side and avoiding using it to save debugging time. You experienced it firsthand in your last question.

Coming back to your question, since you already have a naming scheme for filenames and would like to easily locate a figure generated by externalize, use \tikzsetnextfilename{<my-naming-scheme>} before the tikz image (without spaces!) to set the filename of the figure created.

In the next example, with two sections, \tikzsetnextfilename{FIG_section_\thesection_paraboloid} was used for the first and \tikzsetnextfilename{FIG_section_\thesection_convex} for the second.

After compiling (stackq.tex) the output is

%%  file stackq.tex
\documentclass{article}
% pgfplots
\usepackage{pgfplots}
% uncommenting generates error
\usetikzlibrary{external}
% External lib
\tikzexternalize[
    up to date check={simple},
    prefix=./figures/
] % turn externalization on/off
% Using tikzset generates error
\tikzset{%
    external/system call={%
        lualatex \tikzexternalcheckshellescape
        --halt-on-error
        --shell-escape
        --interaction=batchmode
        --jobname "\image" "\texsource"

    }
}
\pgfplotsset{
    compat  = newest,
    width   = 10cm,    % width
    height  =  7cm,    % height
    samples = 10,
}
\begin{document}
\section{First}
\tikzsetnextfilename{FIG_section_\thesection_paraboloid}% added <<<<<<<<<<<<<<<<<<<<<<
\begin{tikzpicture}
    \begin{axis}[hide axis]
    \addplot3 [
        % Aparence
        surf,
        opacity=0.5,
        fill opacity= 1,
        faceted color = white,
        shader=faceted interp,
        % Scope
        data cs = cart, % cart/polar/polarrad
        % Variable
        domain   = -1:1,
        domain y = -1:1,
    ]{
        x^2-y^2
    };

\end{axis}

\end{tikzpicture}
\section{Second}
\tikzsetnextfilename{FIG_section_\thesection_convex}% added <<<<<<<<<<<<<<<<<<<<<<
\begin{tikzpicture}
    \begin{axis}[hide axis]
    \addplot3 [
        % Aparence
        surf,
        opacity=0.5,
        fill opacity= 1,
        faceted color = white,
        shader=faceted interp,
        % Scope
        data cs = cart, % cart/polar/polarrad
        % Variable
        variable   = u,
        variable y = v,
        domain   = 0:360,
        domain y = -180:0,
    ]
    (
        {cos(u)*sin(v)}, 
        {sin(u)*sin(v)}, 
        {cos(v)}
    );

\end{axis}

\end{tikzpicture}
\end{document}