Linux Shell Scripting Cookbook - Second Edition

Reading the output of a sequence of commands in a variable

One of the best-designed features of shell scripting is the ease of combining many commands or utilities to produce output. The output of one command can appear as the input of another, which passes its output to another command, and so on. The output of this combination can be read in a variable. This recipe illustrates how to combine multiple commands and how its output can be read.

Getting ready

Input is usually fed into a command through stdin or arguments. Output appears as stderr or stdout. While we combine multiple commands, we usually use stdin to give input and stdout to provide an output.

In this context, the commands are called filters . We connect each filter using pipes, the ...