Shell Programming and Scripting

/usr/bin/syslogMailer < /etc/syslog.pipes/criticalMessages

#!/bin/bash

# syslogMailer: a script to read stdin and turn each line into an alert
# email typically this is used to read a named-pipe written to by syslog
#
#   example usage: syslogMailer < /etc/syslog.pipes/criticalMessages
#

alertRecipient="alerts@example.com"  # the mail recipient for alerts
sender="admininstrator@example.net" # the mail sender
TMOUT=1                                 # don't wait > 1 second for input

# process each line of input and produce an alert email
cat <<EOF | sendmail -t -oi
To: ${alertRecipient}
Reply-to: ${sender}
From: ${sender}
Subject: "critical error on syslog"

$(while read line
do
   # remove any repeated messages
   echo ${line} | grep "message repeated" > /dev/null 2>&1
   if test $? -eq 1
   then
      # output the alerts
      echo "${line}"
   fi
done)
EOF

# m h  dom mon dow   command
0-59/5 * * *   *     /usr/bin/syslogMailer < /etc/syslog.pipes/criticalMessages > /dev/null 2>&1

cat /tmp/test
test1
test2

0-59/1 * * *   *     /usr/bin/syslogMailer < /tmp/test > /dev/null 2>&1