Here's an issue that I ran into recently: from version 1.4.20 onwards, lighttpd has stopped passing stderr to CGI processes, should one be peculiar enough to run CGIs on lighttpd (which can be done). If you need error logging from your CGIs, you will have to roll something on your own.

(Fedora 10 has lighttpd 1.4.22 and so is affected by this.)

There is a bug report for this, but I don't know if it has been accepted by the lighttpd developers as an actual bug that will get fixed. That two versions of lighttpd have been released with this issue suggests that, as a minimum, it is not being considered an important issue.

(I suspect that relatively few people use lighttpd to run plain CGIs; most people probably use FastCGI or SCGI instead if they need dynamic things.)

The simplest thing is to just write a cover script for your CGI that dumps standard error into a logfile, but this means that it won't be timestamped. If you need that, you'll have to post-process your program's stderr while leaving standard output alone, which the Bourne shell unfortunately makes rather difficult.

(My solution was to write a program that ran a subordinate command while capturing and timestamping its stderr and leaving its stdout alone. This is relatively trivial in anything that has access to Unix system calls; I wrote mine in C for obscure reasons.)