Linux命令行大全｜读书笔记

Book Notes: The Linux Command Line - Chapter 5

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About this Book 📚

Name: The Linux Command Line

Author: William E. Shotts

Publisher: No Starch Press

Cover:

Translation Version:

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Notes ✍️

4 Types of Commands

• An executable program
  • All files we saw in /usr/bin are executable programs. Within this category, programs can be compiled binaries such as programs written in C and C++, or programs written in scripting languages such as the shell, Perl, Python, Ruby, and so on.
• A built-in command
  • A command built into the shell itself. bash supports a number of commands internally called shell builtins. The cd command, for example, is a shell builtin.
• A shell function
  • Shell functions are miniature shell scripts incorporated into the environment.
• An alias
  • Aliases are commands that we can define by ourselves, built from other commands.

Commands of Chapter 5

• type

  • Display information about command type
  • Examples
    • type ls
    • type cd
    • type mv

• which

  • Display an Executeable’s Location
  • Examples
    • which ls
    • which cp

• help

  • Display information about built-in commands
  • Examples
    • help cd

• --help

  • Display a description of the command’s supported syntax and options
  • Examples
    • mkdir --help
    • mv --help

• man

  • Display a program’s mannual page
  • Examples
    • man mv

• whatis

  • Display one-line manual page descriptions
    • whatis mv
    • whatis cp

• alias

  • Create an alias for a command
  • 🍉 PS: The alias commands disappear when shell session ends, but we will learn how to store them for future use in later chapters.

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Lab 🧑🏻‍💻

Why Labs ?

Lab provides a hands-on learning experience that allows us to apply theoretical knowledge to practical situations. This helps us to better understand concepts and retain information more effectively.

Lab1

use type , which, help, whatis, man to check fundamental commands

• pwd
• cd
• ls
• mkdir
• cp
• mv
• rm
• less
• file

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Lab2

Prerequisites

Try using ; to write commands in 1 line

cd; cd Desktop;

Task

Use alias to change current directory to Desktop

type cdd # check if 'cdd' is used
alias cdd='cd; cd Desktop;' # if not, assgin these command lines to 'cdd'
cdd # use this command