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expr not working

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# 1  
Old 12-31-2010
expr not working
I have written below script which monitors a log file and if log file is not writting for 2 intervels then admin should be notified.

================

Code:
sh=`date | awk '{print $4}' | cut -d ":" -f1`
sm=`date | awk '{print $4}' | cut -d ":" -f2`
lh=`ls -l /opt/Heartbeat.log | awk '{print $8}' | cut -d ":" -                                              f1`
lm=`ls -l /opt/Heartbeat.log | awk '{print $8}' | cut -d ":" -                                              f2`
if [ "$sh" = "$lh" ]
then
  if [ "$sm" = "$lm" ]
  then
    echo "Database written properly"
  else
    echo "Database failed to written"
    echo $x
    x=`expr $x + 1`
    echo $x
    if [ "$x" = "2" ]
    then
      mailx -s "Data base failed written - Need to retrieve missing data" -c "abc@xyz.com"<<EOF
    else
      echo "Hello"
    fi
  fi
else
  echo "Hi"
fi

===============

If i run the above script in Solaris 8 OS, i am getting followin error message. Pls correct me where i wrong.

------ Error Msg -------
Code:
$ sh test.sh
Database not being written

expr: syntax error

Hello

-------------------------


Moderator's Comments:
Mod Comment Please use code tags when posting data and code samples, thank you.
Last edited by Franklin52; 12-31-2010 at 09:37 AM.. Reason: Please indent your code and use code tags
# 2  
Old 12-31-2010
This is because x is not defined/set before it is used in expr.
Following works:
Code:
x=1
x=`expr $x + 1`
echo $x

# 3  
Old 12-31-2010
My requirement is x should be 0 initially and when log not written first time it should increase by 1 and when it fails second time then it should be notified to user.
# 4  
Old 12-31-2010
How long is an "interval"?
# 5  
Old 12-31-2010
Assuming that you are running the script at different times.
So you need a way to track database failure. x is local to the program and you need some external way to track it.
You may use a file for this.
When script runs 1st time, create a file and store 0 in that. Then put new value based on Database failed (increment value) or success (reset to zero).
When script runs next times, read that value, process and put that value back for next time processing.
Create interval file in some directory (say /abc/def/)where user has permission ot create file. Then
Code:
sh=`date | awk '{print $4}' | cut -d ":" -f1`
sm=`date | awk '{print $4}' | cut -d ":" -f2`
lh=`ls -l /opt/Heartbeat.log | awk '{print $8}' | cut -d ":" - f1`
lm=`ls -l /opt/Heartbeat.log | awk '{print $8}' | cut -d ":" - f2`
if [ -f "/abc/def/interval.dat" ]; then
   echo "0" > /abc/def/interval.dat
fi
x=$(cat /abc/def/interval.dat)
if [ "$sh" = "$lh" ]
then
if [ "$sm" = "$lm" ]
then
echo "Database written properly"
echo "0" > /abc/def/interval.dat
else
echo "Database failed to written"
echo $x
x=`expr $x + 1`
echo "$x" > /abc/def/interval.dat
echo $x
if [ "$x" = "2" ]
then
mailx -s "Data base failed written - Need to retrieve missing data" -c "abc@xyz.com"<<EOF
else
echo "Hello"
fi
fi
else
echo "Hi"
fi

# 6  
Old 12-31-2010
I have to point out that the script will not work. Hoping that the update of the heartbeat file and that the invokation this script will occur in same minute, all the time, is not realistic. Cron, which I assume you are using to invoke the script, is not that deterministic. Now if that is why you are running the script twice, it would be far easier to write a script that answers the requirement "has the heartbeatfile been updated since the the last time I checked?" That script would look something like:
Code:
#! /bin/ksh

DBHB=/opt/Heartbeat.log  # updated by database processes
DBCK=/opt/Heartbeat.ck   # created if heartbeat file has not been updated

FMT='%x %H:%M:%S'     # date/time stamp for logfile

#===============================================================================

if [[ ! -f "${DBCK}" ]]; then
    date "+${FMT} - initializing" > ${DBCK}
fi

if [[ ! -f "${DBHB}" ]]; then
    date "+${FMT} - missing ${DBHB}" >> ${DBCK}

    # insert additional commands here

    exit
fi

if [[ "${DBHB}" -nt "${DBCK}" ]]; then
    date "+${FMT} - ok" >> ${DBCK}
else
    date "+${FMT} - database failure" >> ${DBCK}

    # insert additional commands here
fi

exit

Just run this from cron.

If the databases not updating the hearthbeat file for "two intervals" is a requirement, the script would need an additional check file, similar to the interval.dat file used by @anurag.singh, as in:
Code:
#! /bin/ksh

NAME=$(basename ${0})
FILE=/var/log/${NAME}.log # current state of the database

DBHB=/opt/Heartbeat.log  # updated by database processes
DBCK=/opt/Heartbeat.ck   # created if heartbeat file has not been updated

FMT='%x %H:%M:%S'     # date/time stamp for logfiles

#===============================================================================

if [[ ! -f "${FILE}" ]]; then
    date "+${FMT} - initializing" > ${FILE}
fi

if [[ ! -f "${DBHB}" ]]; then
    date "+${FMT} - missing ${DBHB}" >> ${FILE}
    # insert additional commands here
    exit 1
fi


if [[ "${DBHB}" -nt "${FILE}" ]]; then
    #  Everything is ok, the heathbeat file is newer than the logfile

    rm -f "${DBCK}"
    date "+%x %X - ok" >> ${FILE}
    exit 0
fi

#
#  Everything is not ok. If the heathbeat checkfile exists, then this
#  is the second time we detected that the the database hearthbeat
#  file has not been updated, so send out an elert.
#

if [[ -f "${DBCK}" ]]; then
    date "+${FMT} - database failure" >> ${FILE}
    # insert additional commands here
else
    date "+${FMT} - checking database" >> ${FILE}
    touch ${DBCK}
fi

exit 1

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