Run script after yum install & yum update

Hello all,

Would it be possible to run a script every time yum is finished after an 
update or install a package?
I would like to add the priority information in the specific files.
After an upgrade all priority information is missing in the .repo files.

The script looks like this:
#!/bin/bash
# Change the default CentOS repositories files to have priority 2
find /etc/yum.repos.d/Cent*.repo -size +1c > /tmp/files.tmp
while read filename
do
         grep -q "priority=" $filename
         if [ $? -ne 0 ] ; then
                 mv $filename $filename.BG
                 sed  -e "/^\[/a\priority=2" $filename.BG >> $filename
                 rm -f $filename.BG
                 echo $filename
         fi
done < /tmp/files.tmp
rm -f /tmp/files.tmp
# Change the "thirdparty"  repositories files to have priority 12
find /etc/yum.repos.d/*.repo -size +1c > /tmp/files.tmp
while read filename
do
         grep -q "priority=" $filename
         if [ $? -ne 0 ] ; then
                 mv $filename $filename.BG
                 sed  -e "/^\[/a\priority=12" $filename.BG >> $filename
                 rm -f $filename.BG
                 echo $filename
         fi
done < /tmp/files.tmp
rm -f /tmp/files.tmp


Best regards,
Rob