Lilypond server for SPIP

[RICHARD Christophe]

Hi,

I'm working on a system using lilypond to embed music notation 
on dynamicwebsite SPIP (articles and forums) 

http://www.spip.net/en_article88.html

It works fine on local test but i have two little problems to resolve
 before tocreate a publicly accessible webserver.

I'm worried about the possibility that lilypond program hang indefinitely 
and i don't know how using ulimit. Have you more informations about this.

I'm needing to generate all files (ly, midi and png) in a CACHE directory 
andusing the command (in PHP):

$lilypond_bin." --safe --png --output=$cache_dir"." ".$fichier_source."
2> ".$fichier ;

where $cache_dir = "CACHE/lilyspip"; 
and  $lilypond_bin = "/usr/local/bin/lilypond";

It works but i've the message "impossible to change work directory for 
CACHE/lilyspip"  

Is there an an other solution to avoid this message ? 
(the  log file is  insert  into png file if lilypond failed and 
this message is useless for users).

Thanks to your help.

Christophe