Include files in Apache HTTP Server Version 2.2 httpd.conf

The information you're after is all in the logs, so you should look at a log analyzer such as AWStats. The other option is to use Google Analytics.

For analyzing the logs, here's a rough example which you can use to tell you how many MB of traffic a log file reports from the command line:

cat /var/log/apache/access.log | awk '{SUM+=$10}END{print SUM/1024/1024}'

With any *nix application, the easiest method is to query the binary itself. In the case of httpd, I'd imagine the process would be something like this:

$ whereis httpd
/usr/sbin/httpd
$ /usr/sbin/httpd -V
Server version: Apache/2.2.11 (Unix)
Server built:   Jun 17 2009 14:55:13
Server's Module Magic Number: 20051115:21
Server loaded:  APR 1.2.7, APR-Util 1.2.7
Compiled using: APR 1.2.7, APR-Util 1.2.7
Architecture:   64-bit
Server MPM:     Prefork
  threaded:     no
    forked:     yes (variable process count)
Server compiled with....
 -D APACHE_MPM_DIR="server/mpm/prefork"
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
 -D APR_USE_FLOCK_SERIALIZE
 -D APR_USE_PTHREAD_SERIALIZE
 -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=128
 -D HTTPD_ROOT="/usr"
 -D SUEXEC_BIN="/usr/bin/suexec"
 -D DEFAULT_PIDLOG="/private/var/run/httpd.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_LOCKFILE="/private/var/run/accept.lock"
 -D DEFAULT_ERRORLOG="logs/error_log"
 -D AP_TYPES_CONFIG_FILE="/private/etc/apache2/mime.types"
 -D SERVER_CONFIG_FILE="/private/etc/apache2/httpd.conf"

As you can see - my OS X says the binary, if not directed otherwise, will use the config file: /private/etc/apache2/httpd.conf

If that doesn't help, perhaps Christopher's suggestion of find is the next step.