$ cat demo.sh
#!/bin/bash

#build U-Boot
if [ "$1" == 'u' ] || [ "$1" == 'n' ]; then	
	echo "build U-Boot"
	cd bootloader/uboot
	./mk kvim4 --avb2 --vab 
	cd -
fi

#build Kernel
if [ "$1" == 'k' ] || [ "$1" == 'n' ]; then
	echo "build Kernel"
if [ "$2" == 'n' ] || [ "$1" == 'n' ]; then
	. build/envsetup.sh 
	lunch kvim4-userdebug 
	make distclean
fi	
	./mk kvim4 -v 5.4 -j100
fi

#build Android
if [ "$1" == 'a' ] || [ "$1" == 'n' ]; then
	echo "build Android"
if [ "$2" == 'n' ] || [ "$1" == 'n' ]; then
	. build/envsetup.sh 
	lunch kvim4-userdebug 
	make clean
fi	 
	. build/envsetup.sh 
	lunch kvim4-userdebug 
	make installclean
	#make -j80 otapackage
	make -j80
fi