We have megaease.conf, and want to replace the contents in user.conf between the ######### MEGAEASE-BEGIN ########## and ######### MEGAEASE-END ########## lines.
First time, insert the block
echo "######### MEGAEASE-BEGIN ##########" >> user.conf
cat megaease.conf >> user.conf
echo "######### MEGAEASE-END ##########" >> user.conf