[XeTeX] Checking if a font exists

[Philip Taylor (Webmaster, Ret'd)]

Grzegorz Murzynowski wrote:

> And when the 18th output is on (writing to shell), you can put
>
> \immediate\write 18{fc-list "Myriad Pro" > fontcheck.tex}
> \newread\fontcheck
> \immediate\openin\fontcheck="fontcheck.tex"
> \ifeof \fontcheck …

Is the "\immediate" necessary before the \openin at line 3 ?

As I understand it, there are no deferred reads, only
deferred writes, so I am not convinced that the \immediate
adds any value.

Philip Taylor