Why isn't control_auth_cookie being created?

On Ubuntu, how come Tor (0.2.4.20-1) doesn't create control_auth_cookie anywhere on the system after enabling CookieAuthentication in /etc/tor/torrc?

# /etc/init.d/tor start
* Starting tor daemon...                                             [ OK ]
# tail -n 2 /var/log/tor/log
Nov 24 14:09:06.000 [notice] Tor has successfully opened a circuit. Looks like client functionality is working.
Nov 24 14:09:06.000 [notice] Bootstrapped 100%: Done.
# grep "$$DataD\|Cook$$" /etc/tor/torrc

• What makes you think it hasn't? Where did you look for the cookie? How did you enable CookieAuthentication (what value did you set it to)? – Sam Whited Nov 24 '14 at 15:54
• I did a find / -name "control_auth_cookie". I enabled it by uncommenting CookieAuthentication 1. – Mark Boulder Nov 24 '14 at 20:43
• Could you edit your post and insert the output of grep "$$DataD\|Cook$$" /etc/tor/torrc? – Jens Kubieziel Nov 25 '14 at 8:56
• @JensKubieziel all done! – Mark Boulder Nov 25 '14 at 10:41
• So there should be a file in /var/lib/tor/control_auth_cookie. I tested it locally and it worked fine. Has the logfile some hints if something went wrong? – Jens Kubieziel Nov 26 '14 at 20:34

Your Tor is probably under the impression that it has already created one. (Maybe it did and you deleted it?)
Try the following:

• Edit your torrc to set CookieAuthentication to 0
• reset your Tor (kill -HUP or hit x twice in Arm)
• Edit your torrc again to set CookieAuthentication back to 1
Make sure you have a ControlListenAddress and/or ControlPort set.
If you're using the package from universe/net, the /usr/share/tor/tor-service-defaults-torrc file overrides the cookie location to /var/run/tor/control.authcookie. You should be able to find it there, or you can override that setting by adding the following line to /etc/tor/torrc:
CookieAuthFile /var/lib/tor/control_auth_cookie