Using the "Everything Is a File" abstraction

When we introduced device drivers we said that they lay under the Unix file abstraction; that is, in a Unix-like OS, everything is a file. Now, it's time to verify it, so let's see what happens if we try to execute some file-related utility programs against our new driver.

Thanks to our latest modifications to the chrdev_legacy.c file, our driver simulates a file 300 bytes long (see the chrdev_buf[BUF_LEN] buffer where BUF_LEN is set to 300), where we're able to execute read() and write() system calls on it, just as we do on a normal file.

However, we may still have some doubts, so let's consider standard cat or dd commands, as we know they are utilities useful to manipulate files content. For example, in the man pages of the cat command, we can read the following definition:

NAME
       cat - concatenate...