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
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Pipe and pipelines – connecting commands


The outputs of the programs are generally saved in files for further use. Sometimes, temporary files are created in order to use an output of a program as an input to another program. We can avoid creating temporary files and feed the output of a program as an input to another program using bash pipe and pipelines.

Pipe

The pipe denoted by the operator | connects the standard output of a process in the left to the standard input in the right process by inter process communication mechanism. In other words, the | (pipe) connects commands by providing the output of a command as the input to another command.

Consider the following example:

$ cat /proc/cpuinfo | less

Here, the cat command, instead of displaying the content of the /proc/cpuinfo file on stdout, passes its output as an input to the less command. The less command takes the input from cat and displays on the stdout per page.

Another example using pipe is as follows:

$ ps -aux | wc -l    # Showing...