Sometimes is handy to see what number of visitors you had on you site/server based on the access log – in this case Nginx access log. This will count every different IP, so a chunk of these visitors will be bots.

grep "\[13/Jul/2015" /var/log/nginx/access.log | cut -d" " -f1 | sort | uniq | wc -l

Another slightly different variation

cat access_log | awk '{print $1}' | sort | uniq -c | sort -n | tail