Apache2 ( apache webserver ) not restarting

This is an error I've run into a few times. It's rare enough that the second time I saw it, I had a vague memory that it had happened before. The third time though (was within the last week) I remembered and even remembered where the file was located to solve it. Here's the problem....
As far as I know this is an apache2 problem, not prior.
Apache is not running. You try to start apache and receive the message...

Cannot allocate shared memory: (17)File exists apache

Ok, file exists.... what file?

The ssl_scache file is the one that's still there. (At least in my case).

On Mandrake (Mandriva) based systems it's located at /var/log/httpd/ssl_scache , other distributions it may live at /var/log/apache2/ssl_scache. Of course, you could also do this...

find / -iname ssl_scache

to track it down.

Once you've found it, delete it ( rm ssl_scache ), depending on the system you may need to confirm, then try to start apache. (If you're a bit reluctant it's ok to just rename it (mv ssl_cache ssl_cache_stranded ).

I found this happening on a system that had an abrupt shutdown. When the system booted back up the ssl_scache had been stranded by the abruptly stopped system. It could likely be fixed longterm by having the startup script check for it, then remove it if it exists. This may have been fixed in newer releases of apache, but was an issue in the some of the apache2 setups I've seen.