> For the complete documentation index, see [llms.txt](https://blog.syselement.com/tcm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blog.syselement.com/tcm/courses/linux-101/linux101-references.md).

# Linux101 References

* [Linux101 Course](https://academy.tcm-sec.com/p/linux-101)
* [TCM Linux101-Resources](https://github.com/beskridge/Linux101-Resources) - by Brent Eskridge
  * [Supplementary exercises](https://github.com/beskridge/Linux101-Resources/blob/main/exercises.md)

## Introduction

* [Linux Distributions Timeline](https://upload.wikimedia.org/wikipedia/commons/1/1b/Linux_Distribution_Timeline.svg)
  * [Ubuntu](https://ubuntu.com/)
  * [Kali](https://www.kali.org/)
  * [ParrotOS](https://www.parrotsec.org/)
* [VirtualBox Ubuntu Installation](https://ubuntu.com/tutorials/how-to-run-ubuntu-desktop-on-a-virtual-machine-using-virtualbox#1-overview)

## Command Line basics

* [The Linux *man-pages* project](https://www.kernel.org/doc/man-pages/)
* [Explain-Shell](https://explainshell.com/)
* [Shell-How](https://www.shell.how/)
* [Command-not-found](https://command-not-found.com/)
* [ls](https://linuxize.com/post/how-to-list-files-in-linux-using-the-ls-command/)
* [less](https://linuxize.com/post/less-command-in-linux/)
* [cat](https://linuxize.com/post/linux-cat-command/)
* [Bash Aliases](https://linuxize.com/post/how-to-create-bash-aliases/)

## Files and the Filesystem

* [Filesystem Hierarchy Standard](https://refspecs.linuxfoundation.org/FHS_3.0/fhs/index.html)
* [FHS - Wikipedia](https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard)
* [df](https://linuxize.com/post/how-to-check-disk-space-in-linux-using-the-df-command/)
* [du](https://linuxize.com/post/du-command-in-linux/)
  * [Size of a directory](https://linuxize.com/post/how-get-size-of-file-directory-linux/)
* [Absolute vs Relative Path](https://linuxhandbook.com/absolute-vs-relative-path/)
* [cp](https://linuxize.com/post/cp-command-in-linux/)
* [rm](https://linuxize.com/post/rm-command-in-linux/)
* [Shell Expansions](https://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#Shell-Expansions)
* [tail](https://linuxize.com/post/linux-tail-command/)
* [diff](https://linuxize.com/post/diff-command-in-linux/)
* [Soft Link And Hard Link](https://ostechnix.com/explaining-soft-link-and-hard-link-in-linux-with-examples/)
* [tar](https://linuxize.com/post/how-to-create-and-extract-archives-using-the-tar-command-in-linux/)
* [gzip](https://linuxize.com/post/gzip-command-in-linux/)
* [find](https://linuxize.com/post/how-to-find-files-in-linux-using-the-command-line/)
* [which](https://linuxize.com/post/linux-which-command/)
* [locate](https://linuxize.com/post/locate-command-in-linux/)

## Users and Groups

* [UID](https://linuxhandbook.com/uid-linux/)
* [who](https://linuxize.com/post/who-command-in-linux/)
* [/etc/passwd](https://linuxize.com/post/etc-passwd-file/)
* [/etc/shadow](https://linuxize.com/post/etc-shadow-file/)
* [/etc/group](https://linuxize.com/post/how-to-list-groups-in-linux/)
* [Linux File Permissions](https://linuxize.com/post/understanding-linux-file-permissions/)
* [chmod](https://linuxize.com/post/chmod-command-in-linux/)
  * [chmod Calculator](https://nettools.club/chmod_calc)
* [chown](https://linuxize.com/post/linux-chown-command/)
* [sudo](https://linuxize.com/post/sudo-command-in-linux/)
* [passwd](https://linuxize.com/post/how-to-change-user-password-in-ubuntu/)
  * [root password](https://linuxize.com/post/how-to-change-root-password-in-ubuntu/)

## Installing Software

* [Deb Packages install](https://linuxize.com/post/how-to-install-deb-packages-on-ubuntu/)
* [apt](https://linuxize.com/post/how-to-use-apt-command/)
* [Rpm Packages install](https://linuxize.com/post/rpm-command-in-linux/#)
* [yum](https://linuxize.com/post/how-to-install-updates-on-centos/)
* [gcc](https://linuxize.com/post/how-to-install-gcc-on-ubuntu-20-04/)
* [checkinstall](https://help.ubuntu.com/community/CheckInstall)

## Shell basics

* [Common Shells](https://www.tecmint.com/different-types-of-linux-shells/)
* [Bash](https://www.gnu.org/software/bash/manual/bash.html)
* [zsh](https://www.zsh.org/)
  * [Oh My Zsh](https://ohmyz.sh/)
* [Learn Shell](https://www.learnshell.org/)
* [Environment Variables](https://linuxize.com/post/how-to-set-and-list-environment-variables-in-linux/)
* [Bash Startup Files](https://www.gnu.org/software/bash/manual/html_node/Bash-Startup-Files.html)
* [Bash Write to File](https://linuxize.com/post/bash-write-to-file/)
* [History](https://linuxize.com/post/history-command-in-linux/)

## Utilities and File editors

* [grep](https://linuxize.com/post/how-to-use-grep-command-to-search-files-in-linux/)
  * [Regex in Grep](https://linuxize.com/post/regular-expressions-in-grep/)
* [sort](https://www.geeksforgeeks.org/sort-command-linuxunix-examples/)
* [wc](https://linuxize.com/post/linux-wc-command/)
* [sed](https://linuxize.com/post/how-to-use-sed-to-find-and-replace-string-in-files/)
  * [sed Manual - gnu.org](https://www.gnu.org/software/sed/manual/sed.html)
* [awk](https://linuxize.com/post/awk-command/)
  * [awk Manual - gnu.org](https://www.gnu.org/software/gawk/manual/gawk.html)
* [tr](https://linuxize.com/post/linux-tr-command/)
* [ping](https://linuxize.com/post/linux-ping-command/)
* [ifconfig](https://linuxize.com/post/ifconfig-command/)
* [ip](https://linuxize.com/post/linux-ip-command/)
* [Listening Ports](https://linuxize.com/post/check-listening-ports-linux/)
* [scp](https://linuxize.com/post/how-to-use-scp-command-to-securely-transfer-files/)
* [rsync](https://linuxize.com/post/how-to-use-rsync-for-local-and-remote-data-transfer-and-synchronization/)
  * [rsync over SSH](https://linuxize.com/post/how-to-transfer-files-with-rsync-over-ssh/)
* [file](https://linuxize.com/post/linux-file-command/)
* [nano editor](https://www.nano-editor.org/docs.php)
  * [nano usage](https://linuxize.com/post/how-to-use-nano-text-editor/)
  * [nano keyboard shortcuts](https://cheatography.com/bipinthite/cheat-sheets/nano-editor/)
* [vim](https://linuxize.com/post/how-to-save-file-in-vim-quit-editor/)
  * [vim help files](https://vimhelp.org/)
  * [vim cheat sheet](https://cheatography.com/typo209/cheat-sheets/comprehensive-vim-cheat-sheet/)

## Process Management

* [ps](https://linuxize.com/post/ps-command-in-linux/)
  * [pstree](https://linuxize.com/post/pstree-command-in-linux/)
* [top](https://www.geeksforgeeks.org/top-command-in-linux-with-examples/)
  * [htop](https://www.geeksforgeeks.org/htop-command-in-linux-with-examples/)
* [jobs-fg-bg Background processes](https://linuxize.com/post/how-to-run-linux-commands-in-background/)
* [Zombie Process](https://totozhang.github.io/2016-01-16-linux-zombieprocess/)
* [Kill a Process](https://linuxize.com/post/how-to-kill-a-process-in-linux/)
  * [kill](https://linuxize.com/post/kill-command-in-linux/)
  * [pkill](https://linuxize.com/post/pkill-command-in-linux/)
* [sleep](https://linuxize.com/post/how-to-use-linux-sleep-command-to-pause-a-bash-script/)
* [crontab.guru](https://crontab.guru/)
  * [crontab](https://linuxize.com/post/scheduling-cron-jobs-with-crontab/)
  * [List cron jobs](https://linuxize.com/post/how-to-list-cron-jobs-in-linux/)
* [Linux Run Levels](https://likegeeks.com/linux-runlevels/)
  * [Ubuntu Bootup](https://help.ubuntu.com/community/UbuntuBootupHowto)

## Regular Expressions

* [grep Regular Expressions](https://linuxize.com/post/regular-expressions-in-grep/)
  * [grep regex examples](https://www.cyberciti.biz/faq/grep-regular-expressions/)
* [Online RegExr tool](https://regexr.com/)
* [Regex101 tool](https://regex101.com/)
* [Cyrilex tool](https://extendsclass.com/regex-tester.html)
* [EmailRegex Examples](https://emailregex.com/)

## Bash Scripting

* [Bash Shell Scripting - Wikibooks](https://en.wikibooks.org/wiki/Bash_Shell_Scripting)
* [shebang](https://en.wikipedia.org/wiki/Shebang_\(Unix\))

***