Webserver log file error code checking

Following is a script which is installed on wiki:PuffinServer as /usr/local/bin/weblog-erors and which is run via /etc/logrotate.d/nginx and it sends a email with the results just before the log is rotated each day:

/var/log/nginx/*.log {
        daily
        missingok
        rotate 52
        compress
        delaycompress
        notifempty
        create 0640 www-data adm
        sharedscripts
        prerotate
                /usr/local/bin/nginx-logs
                /usr/local/bin/weblog-erors chris@webarchitects.co.uk
                if [ -d /etc/logrotate.d/httpd-prerotate ]; then \
                        run-parts /etc/logrotate.d/httpd-prerotate; \
                fi \
        endscript
        postrotate
                [ ! -f /var/run/nginx.pid ] || kill -USR1 `cat /var/run/nginx.pid`
        endscript
}

The script can also be run on the commend line and piped into a pager, for example:

sudo /usr/local/bin/weblog-erors | less

weblog-erors

#!/bin/bash

# The log file we are checking, best run the script via logrotate,
# for example edit /etc/logrotate.d/nginx to:
#
#   prerotate
#          /usr/local/bin/weblog-erors chris@webarchitects.co.uk
#          if [ -d /etc/logrotate.d/httpd-prerotate ]; then \
#                  run-parts /etc/logrotate.d/httpd-prerotate; \
#          fi \
#   endscript
LOGFILE="/var/log/nginx/access.log"

# Optional email address to send the reults to
EMAIL=$1

# check that the script is being run by root
if [[ "$(id -u)" != "0" ]] ; then
  echo "You must run $0 as root or via sudo" 
  exit 2
fi

# grep for all the ilines with error codes  
ERRORS=$(grep '1.[0|1]" [4|5]0[2|3|4] ' $LOGFILE)
# grep for to totals for these errors codes 
ERRORS_403=$(grep -c '1.[0|1]" 403 ' $LOGFILE)
ERRORS_404=$(grep -c '1.[0|1]" 404 ' $LOGFILE)
ERRORS_502=$(grep -c '1.[0|1]" 502 ' $LOGFILE)
ERRORS_503=$(grep -c '1.[0|1]" 503 ' $LOGFILE)
ERRORS_504=$(grep -c '1.[0|1]" 504 ' $LOGFILE)

# check to see if any errors were found
if [[ $ERRORS ]]; then
  # check for a email address 
  if [[ $EMAIL ]]; then
    # we were supplied with a email address so send the results by email using mutt
    # name of the server
    HOSTNAME=$(hostname)
    # email subject line
    SUBJECT="$ERRORS_403 403, $ERRORS_404 404, $ERRORS_502 502, $ERRORS_503 503 and $ERRORS_504 504 errors from $HOSTNAME"
    echo "$ERRORS" | mutt -s "$SUBJECT" $EMAIL
  # we don't have a email address so display the results of the grep
  else [[ ! $EMAIL ]]
    echo "Supply a email address on the command line to send the following results by email" 
    echo ""
    echo "Total 403 errors: $ERRORS_403"
    echo "Total 404 errors: $ERRORS_404"
    echo "Total 502 errors: $ERRORS_502"
    echo "Total 503 errors: $ERRORS_503"
    echo "Total 504 errors: $ERRORS_504"
    echo ""
    echo "Lines with errors from $LOGFILE"
    echo ""
    echo "$ERRORS" 
    echo ""
    echo "This script is best piped into a pager, eg:"
    echo "$0 | less"
  fi
else
   # we don't want any output if a email address is specified as the script is run via cron
   if [[ ! $EMAIL ]] ; then
     echo "No recent 403, 404, 502, 503 or 504 errors were found" 
   fi
fi