Raspberry Pi_Eng_10.0 Chapter 10 Understanding Shell Command

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Chapter 10 Understanding Shell Command

Chapter’s Main Topics

This chapter describes the Shell command. It will first explain the basics of the Shell command, explain how to use the Shell command, and then describe the most basic Shell commands. We will not cover all the Shell commands here, and commands associated with a particular topic will be discussed together when dealing with the topic.

It includes descriptions on the following topics:
■ Command overview

■ Shell environment

■ Shell and profile

■ Basic command

■ Operation processing related commands

■ Selective execution related commands

■ Program execution related commands

■ Input and output adjustments related commands

■ Data manipulation related commands

■ System information related commands

Raspberry Pi_Eng_20.2.2 How Shell Runs Commands

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20.2.2 How Shell Runs Commands

20.2.2.1 Types of Kernel’s System Calls

● “fork” system call

This call is one of the system call methods that a process uses to execute another process. When a command needs to be executed, a child process is created and executed separately.