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0101 | Getting Started

Getting Started​

Disclaimer | Attribution​

This short "Introduction to Linux" is based on my own notes taken during the TCM Security - Linux 101 video course by Brent Eskridge, PhD.

I highly recommend this course as a great starting point for learning about Linux; it was instrumental in my own understanding of the subject. I would like to extend a big thank you to the TCM Security Team for providing such valuable resources!

Linux Distributions​

What is Linux?​

  • Open Source operating system (OS)
  • OS is a resource manager
    • Processor time
    • Memory
    • Storage space
  • Kernel
    • Core of the OS
    • Lowest level of the OS

What is a Linux Distribution?​

  • Desktop environment
  • Package managers
  • Applications
  • Goals/Aims/Philosophy

Introduction to the Command Line​

Basic commands | whoami; hostname; pwd; ls; cd​

  • print effective userid: whoami
  • show or set the system's host name: hostname
  • print name of current/working directory: pwd
  • list directory contents: ls
  • change the shell working directory: cd

Getting help commands | man <command>; info <command>; <command> --help​

  • an interface to the system reference manuals
    • man <command>
  • read Info documents
    • info <command>
  • display this help and exit
    • <command> -h or <command> --help

Getting help from "explainshell"​

  • https://explainshell.com

Looking at text files | more; less​

  • a filter for paging through text one screenful at a time
    • more
  • a program similar to more, but it has many more features
    • less

Another way to look at text files | cat​

  • concatenate files
    • cat file1.txt file3.txt
  • number all the output lines
    • cat -n file1.txt file3.txt
  • calling without a file
    • cat
    • echoes everything we type
  • redirect the output
    • cat file1.txt file3.txt > combined.txt
  • redirect the output, without specifying an input file (what you type)
    • cat > new-file.txt