Compiling and installing the scull devices:
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1. Execute Make: 
   make
2. If scull devices already exist then unload them first.
   sudo ./scull_unload
   This may ask you for your root password.
3. Load scull devices
   sudo ./scull_load
4. Check that devices are properly created.
   ls -ltr /dev/scull*
5. Change device permissions to 777
   sudo chmod 777 /dev/scull*

Testing the functioning of scull pipe devices:
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- Open a terminal window and write some data to the scull device using the following command: echo "Hello World" > /dev/scull0
- Check that the data is written to the device: more /dev/scull0
- Write some other data to the scull device: echo "Good bye" > /dev/scull0
- Observe that the earlier string, "Hello World", is overwritten by the string "Good bye".