Shell Programming and Scripting

 
firts in your cron                            
0,30 *, *, *, * /path/script.sh               
                                              
cat script.sh                                 
#!/bin/ksh                                    
                                              
LOG=$(date +file_%d%m%Y_%k%M)                 
DIRECTORY=$(date +dir_%d%m%Y)                 
cp biggest_log > $LOG                         
>biggest_log                                  
grep ERROR $LOG > $DIRECTORY/temporal.log     
cat $DIRECTORY/temporal.log >> $DIRECTORY/$LOG

#!/bin/sh 
COUNT=""
HNAME=$(uname -n)
SDATE=$(date +"%h-%d-%y")__$(date +"%k-%M").log
LOGCHK="/var/log/syslog:Sending%20on|avahi-daemon|Listenning%20on /var/log/daemon.log:ntpdate|dhclient"
cd /home/guto/SCRIPT/LogMonitor/
for CLOG in $LOGCHK
 do
    #setting the dynamic variables
    LOGFILE="`echo $CLOG | cut -d: -f1`"
    EXPRETION="`echo $CLOG | cut -d: -f2`"
    EXPRETION="`echo $EXPRETION |sed -e \"s/%20/ /g\"`"
    SUFX="`echo $LOGFILE |sed -e s/\\\//_/g`"
    SUFX="`echo $SUFX |sed -e \"s/\\\./_/\"`"
    #check for the first run (this segment should run only once)
    if [ "`eval echo '$COUNT'${SUFX}`" = "" ]; then
       eval \ BASE${SUFX}=`wc -l $LOGFILE |awk '{ print $1 }'`            #gets initial length of logfile
       egrep -iw "\"$EXPRETION\"" $LOGFILE > ${HNAME}__${SUFX}__${SDATE}        #greps the expretions and saves to the new file
    fi
    
    eval COUNT${SUFX}=`wc -l $LOGFILE |awk '{ print $1 }'`                        #gets the current length of logfile
    
    #this segment takes care of on going growth of the log    
    if [ `eval echo '$COUNT'${SUFX}` -gt `eval echo '$BASE'${SUFX}` ]; then
       CLINES=`eval expr '$COUNT'${SUFX} - '$BASE'${SUFX}`
       eval \ BASE${SUFX}='$COUNT'${SUFX}
       tail -$CLINES $LOGFILE |egrep -iw "\"$EXPRETION\"" > ${HNAME}__${SUFX}__${SDATE}        #greps the expretions and saves to the new file
       
    #this segment resets the count & base variables when the logfile is rotated at night.
    elif [ `eval echo '$COUNT'${SUFX}` -lt `eval echo '$BASE'${SUFX}` ]; then
       eval \ BASE${SUFX}='$COUNT'${SUFX}                                #gets initial length of logfile after the rotation
       tail -$CLINE $LOGFILE |egrep -iw "\"$EXPRETION\"" $LOGFILE > ${HNAME}__${SUFX}__${SDATE}    #greps the expretions and saves to the new file 
    fi
 done