i have this script that checks for yesterday date and also specific hour in that

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


TZ=`date +%Z`+24 ;a=`date +%Y-%m-%d %k`
cd logs
count=0
for i in DBMaint.log
do

cat $i | grep $a >> file12.txt
done
----------------------------------------------------------------

here k=hour which i want to set it to 22.how to do that.

actually i want to grep yesterday date and in that 22nd hour ,so how to specify that in below command


TZ=`date +%Z`+24 ;a=`date +%Y-%m-%d %k`
------------------------------------------------------------
how to set the desired value in above command for hour