TEXINPUTS, TEXMF and other variables

Question

While investigating some things about TeX, I stumbled across TEXINPUTS, which one can use to tell (La/pdf/..?)TeX where to find it's files. I decided to look into it a bit closer and learned about kpathsea, which seems to be where TEXINPUTS is used to guide file search. kpathsea also defines some other variables, like TEXMFHOME, TEXMFDIST and most importantly TEXMF, which is used in the definition of TEXINPUTS in the texmf.cnf file: TEXINPUTS = $TEXMFDOTDIR;$TEXMF/tex/{$progname,generic,latex,}//.

Therefore, one can read the order in which the texmf trees are searched (by default) from the definition of TEXMF.

What I am curious about is whether this works not only with TeX Live, but also MikTeX and other distributions. The texmf.cnf file is located in a subfolder of texlive. According to Christian Schenk's comment on this post, MikTeX does not use kpathsea but rather an emulation of it. MikTeX also has an env-var called TEXINPUTS, but I couldn't find anything about the other TEXMF variables.

If MikTeX does not use the TEXMF variable, how is the precedence of the different trees / roots handled?

Answer 1

I don't know about the use of TEXMF, but I think I can infer a conclusion for you. I do use TEXINPUTS with MiKTeX (Windows). Its behavior is not consistent with my texliveFull installation (Nix Home Manager on Linux)

How to use TEXINPUTS with MiKTeX? For MiKTeX I must declare:

#!/usr/bin/env bash
(export TEXINPUTS="$DATA_DIR" && pdflatex $TARGET_FILE)

For Texlive I must declare:

#!/usr/bin/env bash
(export TEXINPUTS=".;$DATA_DIR;" && pdflatex $TARGET_FILE)

I grep the result of pdflatex --version for "MiKTeX" and if present, use "$DATA_DIR" and otherwise use ".;$DATA_DIR;" for cross-platform compatibility.

This could be done as part of a bash script:

#!/usr/bin/env bash
if pdflatex --version | grep -q 'MiKTeX'; then
  (export TEXINPUTS="$DATA_DIR" && pdflatex "$TARGET_FILE")
else
  (export TEXINPUTS=".;$DATA_DIR;" && pdflatex "$TARGET_FILE")
fi

I do this in a Makefile:

$(OUT_DIR)/%.pdf : $(BUILD_DIR)/%.tex
    @mkdir -p "$(OUT_DIR)"
    @echo "Compiling $(BOLD)$@$(SGR0)..."
    @if pdflatex --version | grep -q 'MiKTeX'; then \
        (export TEXINPUTS="$(DATA_DIR)" && pdflatex "$TARGET_FILE") \
    else \
        (export TEXINPUTS=".;$(DATA_DIR);" && pdflatex "$TARGET_FILE") \
    fi

Because the behavior of TEXINPUTS is different from other pdflatex distributions, and TEXMF is not listed in the documentation, I think it is safe to assume that TEXMF is not supported by MiKTeX.