if [ condition ]; then
	action
elif [ condition ]; then
	action
else
	action
fi

Examples

Example 1

if grep Ford students
then
	echo end of list
else
	echo No student named ford
fi

Example 2

if test $x -lt 3
then
	echo this is very suprising
fi

Example 3

if [ $# -lt 1 ] then
	echo "mymsg"
fi