More reliable than grep -ir /etc/apache2

If you're running Apache you'll often find you need to find the config for a vhost given a serveralias, or the logfile of the site served out of a particular directory. This aims to be a faster and more reliable way of doing that than grepping:

avi@donkey:$ a2 avi.co
servername            avi.co
documentroot          /home/avi/wordpress
errorlog              /home/avi/logs/error_log
customlog             /home/avi/logs/access_log combined
serveralias           avi.co, www.avi.co, aviswebsite.co.uk, www.aviswebsite.co.uk
sockets               10.20.30.10:80
file                  /etc/apache2/sites-enabled/avi.co.conf

If the argument begins with a forward-slash, it is assumed to be a path, and so the log, docroot, ssl key/cert and config file paths are checked, rather than servernames and aliases:

avi@donkey:~$ a2 /home/avi/logs/pics_error_log 
servername            pics.avi.co
documentroot          /home/avi/pics_html
errorlog              /home/avi/logs/pics_error_log
serveralias           pics.avi.co
sockets               10.20.30.10:80
file                  /etc/apache2/sites-enabled/pics.avi.co

and, if you know what you want, you can have it just give the path either to the document root or apache's config file (for all matching vhosts):

vim `a2 avi.co -f`

cd `a2 avi.co -d`

I had a look through the various Apache config-file parsing moduls on the CPAN and each was lacking one of an ability to deal with included config files, or an ability to deal with a series of virtualhosts with identical opening tags (all on the same socket); they are for using Apache-like configs, not actually parsing Apache's config.

parse_apache_config() is therefore small, inelegant and single-use. It has its limitations (not least that it can't deal with an Include inside a vhosts) but it's generally good enough at the moment. If this is useful but needs to be able to more properly parse the configs it may end up making use of one of those, but for now, as a single-script, I think it's fine :)