i have a ksh script :

#!/bin/ksh
TZ=`date +%Z`+24 ;a=`date +%Y-%m-%d`

b=`date +"%H:%M:%S"`
cd /ednadtu3/u01/pipe/logs
for i in Archiver1.log
do

cat $i | grep $a | grep $b >> /ednadtu3/u01/pipe/naveed/Insert_Date.txt
done
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here i want to grep certain given values of hour in file Archiver1.log.
but this script greps current time of system. i want to grep 20th hour in file Archiver1.log. how to do that.

actually i want to insert the own values in below format

b=`date +"%H:%M:%S"`

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