The problem is that, after they restart their computers, they find that the Audio Input and Output devices have been uninstalled, and they have to reinstall them to get them working again.

If you have multiple audio inputs or outputs connected to your Mac, then you’re probably aware that you can visit System Preferences to manage and switch between interfaces at will. But wouldn ...

The standard input or stdin device to give commands is the keyboard ... In the above instance, the cat command is used to read the file music.mp3. It sends the output to the audio device /dev/audio.