Weird unasked-for file trace in LaTeX

[David Carlisle]

The map file line is shown on the terminal by default, even without
your tracing lines the output is


$ pdflatex cc393
This is pdfTeX, Version 3.14159265-2.6-1.40.20 (TeX Live 2019)
(preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./cc393.tex
LaTeX2e <2019-10-01> patch level 3
(/usr/local/texlive/2019/texmf-dist/tex/latex/base/article.cls
Document Class: article 2019/10/25 v1.4k Standard LaTeX document class
(/usr/local/texlive/2019/texmf-dist/tex/latex/base/size10.clo))
No file cc393.aux.
[1{/usr/local/texlive/2019/texmf-var/fonts/map/pdftex/updmap/pdftex.map}]
(./cc393.aux) )</usr/local/texlive/2019/texmf-dist/fonts/type1/public/amsfonts/
cm/cmr10.pfb>
Output written on cc393.pdf (1 page, 12027 bytes).
Transcript written on cc393.log.

You see the same with the plain TeX

Hello, world!

\bye

It comes between the [ (the start of the output routine) and 1] (page
1 being shipped out) as that i the first time it needs to access the
map file.

You can force it to be loaded earlier, before the [ is output by adding

\pdfmapfile{pdftex.map}

to the top of the file.

David