Linux Shell Scripting Cookbook - Third Edition

Getting ready

As mentioned previously, Unix handles everything as files. Every device is a file. Hence, if we want to copy an exact image of a device, we need to read all data from it and write to a file. An optical media reader will be in the /dev folder with a name such as /dev/cdrom, /dev/dvd, or perhaps /dev/sd0. Be careful when accessing an sd*. Multiple disk-type devices are named sd#. Your hard drive may be sd0 and the CD-ROM sd1, for instance.

The cat command will read any data, and redirection will write that data to a file. This works, but we'll also see better ways to do it.