One-liners

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Common Error/Limit identification 

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Apache MaxRequestWorkers

grep -i 'MaxRequestWorkers' $(locate apache || locate httpd | grep -iE "error.log$")

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PHP Max_Children

Check for all logged instances of max_children limit being reached - prints each occurrence. Remember, max_children being reached is usually the symptom of  a larger issue - probably traffic.

grep -i max_children $(locate fpm | grep -iE "error.log$")  

Check for all instances of max_children from today's date in the logs, and output as a count for each domains number of occurrences. (untested)

grep -i max_children $(locate fpm | grep -iE "error.log$") | grep -i "$(date +%d-%b)" | cut -d' ' -f5 | tr -d ']' | sort | uniq -c | sort -nr | awk 'BEGIN {print "Total PHP max_children errors on " strftime("%d-%b-%Y")}; {print $0}'

Check specific date's occurrences of PHP max_children being reached (date needs updating to desired date.)

grep -i max_children $(locate fpm | grep -iE "error.log$") | grep -i '10-jul' | cut -d' ' -f5 | tr -d ']' | sort | uniq -c | sort -nr | awk 'BEGIN {print "Total PHP max_children errors today"}; {print $0}' 

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PHP Memory Limit

Search logs for instances of PHP memory_limit being reached: (untested)

grep -i 'Fatal error: Allowed memory size of' $(find / -iname "*error.log")

or

grep -i  'Fatal error: Allowed memory size of' $(locate "*.ini")

Check domain PHP memory_limit values:

grep -i 'memory_limit' $(find / -iname "*.ini")

or

grep -i 'memory_limit' $(locate "*.ini")

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Traffic Analysis

(File paths will need updating for these commands)

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wp-login requests

grep -i 'wp-login' /path/to/access/log | cut -d ':' -f1 | sort | uniq -c

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XML-RPC requests

grep -i 'xmlrpc' /path/to/access/log | cut -d ':' -f1 | sort | uniq -c

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bot traffic user agents

 awk -F'"' '{print $6}' /var/www/vhosts/domain/logs/access_ssl_log | sort | uniq -c | sort -nr | head -20 | grep -iE 'bot|crawler'

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MySQL Tuner

wget -O mysqltuner.pl mysqltuner.pl && perl mysqltuner.pl

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