I have the following directive in my nginx.conf file:

map $http_user_agent $is_bot {
default 0;
~*(crawl|Google|Slurp|bingbot|tracker|click|parser|msnbot|msnbot|Gigabot|spider) 1;
}

This works just fine on a server running PHP 5.3 and nginx 1.1.19. It's causing an invalid option error when I try to start nginx on a different server running PHP 5.5 and nginx 1.4.6:

nginx: invalid option: "~*(crawl|Google|Slurp|bingbot|tracker|click|parser|msnbot|msnbot|Gigabot|spider)"

If I remove "|spider" the problem goes away. What could be wrong with this expression when it includes "spider"?

A little more testing has identified "spid" as the issue, not "spider", but I have no idea why that would create a regular expression problem. Clues, please?

Sounds like a bug, report it here http://trac.nginx.org/nginx/report/1?sort=ticket&asc=0&page=1

Done! Thanks for the suggestion.

http://trac.nginx.org/nginx/ticket/551

The ticket was closed as invalid with this comment:

"This doesn't looks like a problem in nginx. Rather, it's an incorrect assumption in init.d script you use - looks like it tries to grep nginx.conf for the "pid" directive, and fails to do it properly. Ask your package maintainer for a refund."

Indeed, /etc/init.d/nginx does this:

PID=$(awk -F'[ \t;]+' '/[^#]pid/ {print $2}' /etc/nginx/nginx.conf)

Which finds the (unintended) wrong line in my config file. I've implemented a work-around for now (changing the "p" in "spider" to "\160"). Now I just need to find the right place to report the bug. I'm using Ubuntu 14.04 LTS and this worked fine with 12.04 LTS. The nginx script has definitely changed from 12.04 to 14.04.

Bug reported and confirmed:

https://bugs.launchpad.net/ubuntu/+source/nginx/+bug/1314740