Android system attributes ro, persist, net

System properties ro, persist, net in Framework

1. System properties starting with ro
If the property name starts with "ro.", then this property is regarded as a read-only property. Once set, the attribute value cannot be changed. Restart will not fail, it is an eternal fixed value, and the value cannot be modified; it can only be changed by flashing.
2. System properties starting
with persist If the property name starts with "persist.", when this property is set, its value will also be written to /data/property. This attribute can be modified, and it will be the modified attribute after restarting.
3. System properties starting with net
If the property name starts with "net.", when setting this property, the "net.change" property will be automatically set to add to the last modified property name.

4. Other attributes: They are all temporarily stored in the memory, and will be invalid after restarting.