Book Image

Linux Shell Scripting Essentials

By : Sinny Kumari, Khem Raj
Book Image

Linux Shell Scripting Essentials

By: Sinny Kumari, Khem Raj

Overview of this book

Table of Contents (15 chapters)
Linux Shell Scripting Essentials
About the Author
About the Reviewers

Process substitution

We know that we can use a pipe to provide the output of a command as an input to another command. For example:

$ cat file.txt | less

Here, the cat command output—that is, the content of file.txt—is passed to the less command as an input. We can redirect the output of only one process (cat process in this example) as an input to another process.

We may need to feed the output of multiple processes as an input to another process. In such a case, process substitution is used. Process substitution allows a process to take the input from the output of one or more processes rather than a file.

The syntax of using process substitution is as follows:

To substitute input file(s) by list



To substitute output file(s) by list


Here, list is a command or a pipeline of commands. Process substitution makes a list act like a file, which is done by giving list a name and then substituting that name in the command line.

Diffing the output of two processes

To compare...