The document below compiles fine with pdflatex (MiKTeX-pdfTeX 2.9.4535 (1.40.13) (MiKTeX 2.9)) but the last \write18 call fails with lualatex (Version beta-0.70.2 (MiKTeX 2.9)) with the error: Overfull \hbox (22.4968pt too wide) in paragraph at lines 9--9 [][]\OT1/cmtt/m/n/10 \immediate\write18{"grep" "string with spaces" \jobname.te x > tmp.txt}[] 'grep" "string' is not recognized as an internal or external command, operable program or batch file. % testdoc \documentclass{article} \usepackage{verbatim} \begin{document} \immediate\write18{grep "string with spaces" \jobname.tex > tmp.txt} \verbatiminput{tmp.txt} \immediate\write18{grep "string with spaces" "\jobname.tex" > tmp.txt} \verbatiminput{tmp.txt} % Does not work with luaLaTeX \immediate\write18{"grep" "string with spaces" \jobname.tex > tmp.txt} \verbatiminput{tmp.txt} \end{document} is this intentional?