I) Linux command

1.1 to give the value, no need space after equality operator

yes:
num2=“W3Cschool”
no:
num2 = “W3Cschool”

1.2 true and false in Linux, which is contrary with C language

In Linux: 0 true 1 false
At C: 0 false 1 true

1.3

II) Linux Shell

2.1) with or without single quote mark or double quote mark, to define the array element will be agreeable

my_array=(A B 'C' "D弟~~")echo "第一个元素为: ${my_array[0]}"
echo "第二个元素为: ${my_array[1]}"
echo "第三个元素为: ${my_array[2]}"
echo "第四个元素为: ${my_array[3]}"echo "elements of array are: ${my_array[*]}"
echo "factors of array are: ${my_array[@]}"
```