Mastering Bash

I/O redirection

As we saw in the previous pages, redirection is one of the last operations undertaken by Bash to parse and prepare the command line that will lead to the execution of a command. But what is a redirection? You can easily guess from your everyday experience. It means taking a stream that goes from one point to another and making it go somewhere else, like changing the flow of a river and making it go somewhere else. In Linux and Unix, it is quite the same, just keep in mind the following two principles:

• In Unix, each process, except for daemons, is supposed to be connected to a standard input, standard output, and standard error device
• Every device in Unix is represented by a file

You can also think of these devices as streams: ...