awk/grep commands for Rails log analysis

awk-example.sh

# Access number
cat production.log | grep "^Processing" | wc | awk '{print $1}'

# Each IP access number
cat production.log | grep “^Processing” | awk ‘{print $4}’ | uniq -c 

# Independent IP number
cat production.log | grep "^Processing" | awk '{print $4}' | uniq | wc | awk '{print $1}'
cat production.log | grep “^Processing” | awk ‘{print $4}’ | uniq | wc -l 

# Account number for each pages
cat production.log |grep “200 OK” | awk ‘{print $17}’ | sort | uniq -c 

# Exception info
cat production.log | grep "Error" -6 -n > error.log

# Send exception info to specify email
cat production.log | grep "Error" -6 -n | mail -s "Error Logs" recipient@domain.com

# Time-consuming actions
cat production.log | grep "200 OK" | awk '{print $17}'| sort | uniq -c | sort -r -n | head -n 500 > stat.log

# Top 200 IPs
grep Processing production.log | awk '{print $4}' | sort | uniq -c | sort -r -n | head -n 200 > top-200-ip.log

find the index where you want to start printing (index of $5 in $0) and print the substring of $0 starting at that index.
awk '{print substr($0,index($0,$5))}'
E.g
I, [2015-12-10T03:19:02.378362 #12408] INFO -- : Completed 200 OK in 21ms (Views: 3.3ms | ActiveRecord: 0.8ms)
result
21ms (Views: 3.3ms | ActiveRecord: 0.8ms)