[tex-live] an issue with running dvipdfmx from a makefile

[jfbu]

Hi,

I am not quite sure this is the correct list, and I even
suspect the issue has not much to do with dvipdfmx, but
much more with my ignorance of shell scripts and makefiles

I have a /bin/sh script which runs dvipdfmx. And I have a
makefile which runs the shell script. (see below)

When I do make test, I get

dvipdfmx:warning: Failed to create temporary input file for PSTricks image conversion.

When I use directly the script.sh from the command line 
there is no such warning

This happens with a minimal latex file as source of the dvi

///original latex source
\documentclass{article}
\begin{document}Hello\end{document}
\\\ end of temp.tex

///contents of makefile:
test:
	chmod u+x script.sh; ./script.sh

\\\end of makefile

///contents of script.sh
#!/bin/sh

dvipdfmx temp.dvi

\\\end of script.sh

What should I know better?

Sincerely
Jean-Francois