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

Process management


Managing processes is very important because processes are what consumes system resources. System users should be careful about the processes they are creating, in order to ensure that a process is not affecting any other critical processes.

Process creation and execution

In bash, creating a process is very easy. When a program is executed, a new process is created. In a Linux or Unix-based system, when a new process is created, a unique ID is assigned to it, which is known as PID. A PID value is always a positive number starting from 1. Depending upon a system having init or systemd, they always get the PID value 1 because this will be the first process in a system and it is the ancestor of all other processes.

The maximum value of PID is defined in the pid_max file, which should be available in the /proc/sys/kernel/ directory. By default, the pid_max file contains the value 32768 (max PID + 1), which means a maximum of 32767 processes can exist in a system simultaneously...