When using mathopd to serve ikiwiki, be careful of your Umask settings in the mathopd.conf.

With Umask 026 in mathopd.conf, editing pages resulted in the following errors and a 404 page when the wiki tried to take me to the updated page.

append_indexes: cannot open .../[destdir]/[outputfile].html
open: Permission denied

With Umask 022 in mathopd.conf, editing pages works.

Hopefully this prevents someone else from spending ~2 hours figuring out why this wouldn't work.

More generally, if your web server uses a nonstandard umask or you're getting permissions related problems in the cgi log when using ikiwiki, you can force ikiwiki to use a sane umask via the umask setting in ikiwiki's own setup file. --Joey