Linux Commands
​• ac : prints stats about a users connect time in hours, $ac -pd shows daily user connect time (​psacct needs to be installed and running first)
• anacron : cron job scheduler for a system that is not running 24 hours a day.
• arch : same as uname -m, prints the machine name
• atop :  daily logging, like htop, may need to download
• bat :  cat clone, download here
• bmon : bandwidth monitor
• cat /etc/*release : gives you linux / debian release info
• cat /proc/info : gives you processor info
• ccze : log colorizer, useful for reading var/log/messages (ex. “$sudo tailf /varl/og/messages I ccze” or “$sudo cat /var/log/messages / ccze -m ansi |less -r”)​
• cd - : sends the user to the last directory they were in before the present one
• clear : clears the screen
• ctrl-a / ctrl- e : “$ctrl-a” go to the beginning of a line, “$ctrl-e” go to the end of the line
• ctrl-z : pauses the running process, "$bg" to background, "$fg" to return it to the foreground
• df- h : space on volumes, human readable​
• dig : DNS lookup utility
• dmesg -H : (H flag not available on all systems) boostrap info
• du -hs : directory sizes, human readable
• eject : eject removable media (as in an attached USB flash drive, etc)
• env : shows you some info on the shell environment
• mkdir -p : creates full path ex. "$sudo makdir -p home/Maildir/{cur,new,tmp}"
• export VISUAL=nano; visudo : sets nano as the visudo editor
• find /etc -name *conf : finds and displays all the config files under /etc
• free -h : show you available space on disks, in human readable format
• grep -Pri : searches for text tin the directory and subdirectories and puts it on the screen, ex: "$grep -Pri ." searches current directory
• head : lists top of file
• inode : contains all the information about any linux / Unix file, is an address to a specific disk block, IS the unix file except for the name, which is stored in the directory (together with the inode number) as a reference to the inode data. It truly is the file; the name one sees in the directory is just a reference.
• inxi -Finc 0 > system_data.txt : Creates a file that lists a huge amount of system hardware related details, somewhat like the Windows "C:\ systeminfo" command, requires downloading inxi (click here for details)
• kill $(pgrep mozilla) : Kills all processes associated with Mozilla Firefox, substitute the app name for "mozilla" to kill it.
• lastlog : Shows all users that have logged in (or have the capability to login) and the dates and times of their logins, to limit this to those users who have logged in at some point use "$lastlog |grep -iv never"
• ldd :  Lists the library dependencies of an executable
• less : Pager, shows any text document where you can move through the document by one line, and or page, at a time
• locate :  (run"$sudo updatedb" first): fast search for files
• logsave : saves command / terminal/ ssh session output to a file on the desktop with a timestamp
• lsblk : lists all the block devices / partitions of the system
• lslogins -u : show all users with logins, “$lslogins -Lu” show last user logins
• lsof : list of open files on the system, may require downloading lsof
• lvm : logical volume manager for LUNs and disk partitions
​• man -f : lists details associated with the commands must run "$sudo makewhatis" first
• man -k : searches man pages for the word or string 
• man ascii : outputs an ascii table
• nano: text editor, ex “$nano mytext”, may require downloading nano
• ncdu -rx / : Scans the existing file system and orders directories by largest to smallest data size, fantastic for finding where all the free space has gone (think WinDirTree ), may require downloading ncdu
• nl: adds line numbers to a file
• nmblookup -A : get the (Windows) netbios name from an IP address
• nmon / glances : tools for displaying realtime stats on the system, may require downloading 
• pstree -p : shows processes and PID in a tree format, very useful
• pushd / popd : collects directories to a stack, moves between stack items
• rev : reverses the output (as in “$sudo cat var/log/messages |rev”)
• rpm -qa --last : shows files installed in descending order
• rpm -qa : list all installed apps
• rpm -qa --last |head : shows recently installed files
• screen : for creating virtual terminals (more useful if logged in remotely, such as by ssh)
• script : logs all transactions of a terminal to a file
• set : shows other shell environmental variables
• ss : socket statistics, "$ss -a |grep -E "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b|[^a-z][^:]:[^:][^:][0-9]" provides only sockets that are attached to an or any IP address.
• stat : provides user /group data for the file or directory, ex. “$sudo stat myfile”
• su - : root privallages and root environment, use with caution
• su : root privallages but keeps the current user environment, good for debugging
• sudo -k : kills the sudo timer so root access isn't kept
• sudo -s : Open a shell account with root privileges, use with caution
• sudo !! : does the previous command again and puts ""sudo"" in front"
• sudo cat /etc/passwd : show list of users on the system, “$sudo cat /etc/passwd |grep -iv nologin” show all users with logins
• sudo yum makecache fast : update yum fast mirror package index
• tail : lists end of file
• uname -a : gives you linux kernel information
• users : lists users on the system ("$w" and "$last" are also helpful)"
• visudo : safe secure way of editting the etc/sudoers file, locks the file, checks syntax
• yum check-update : shows programs on the system that have available updates
… & more Linux commands here

Linux Apps
​1. Apache / NGINX power the web
2. Docker, Vagrant, KVM, VirtualBox, & VMWare power system deployment
3. RedHat Enterprise Linux (RHEL), Suse Linux Enterprise Server (SLES), CentOS, Debian and Windows Server are the OS’s that power the web
4. Glances, htop, gtop, bmon and Inixi are for monitoring system behavior
5. Exa, ccze, lnav and cat are for viewing stuff in the command line
6. Nano and vim and  are for editing
7. Brackets, pycharm, and spyder are for python development
8. ELinks is for browsing the web via the command line
9. Shorewall as a system based firewall
10. Webmin for controlling Linux servers via the web
11. Fishshell as a bash replacement, check out it’s command tab completion (start typing a command, or type a command + space, then tab, to see options / flags), want to learn more? Check this out
12. Tilix as terminal emulator
13. Grsync / rsync for backup
14. Brasero cd/dvd burning gnome desktop utility
15. Nbtscan - netbios scanner
16. Mc - “Midnight Comander” a command line, terminal “DOS-like” visual interface that interactively does the work of ls, mv, cp, rm, mkdir, and ftp (and their clones like exa), useful for beginners and or those who like graphics.
17. Micro - Most Linux users know of the editors Vim, and perhaps Nano (see above); Micro is another editor with easy to learn commands (like ctrl-s for save) plus syntax highlighting ...
18. Pi-Hole, a DNS blackhole that can be loaded on several different versions of Linux (including Debian Ubuntu), to keep ads away from your PC / Mac
18. TLDR - Useful examples to a large list of Linux / Mac and Windows commands (did you know that tldr means "to long didn't read"? Now you do ... ), see below for the TLDR master list as a PDF
TLDR - Linux Manual.pdf
File Size: 481 kb
File Type: pdf
Download File

Must-have Command Line Apps
Shell Replacements:
  1. Fish - "Friendly interactive shell", shell replacement for BASH, provides syntax coloring, tab completions, themes and well awesomeness 
  2. Zsh / Oh my Zsh - Shell replacement for BASH if you need / want POSIX compliance (if you don't know what POSIX is, we recommend Fish)

Tools:
  1. Micro - As discussed above, a really cool text editor that provides syntax highlighting and more (otherwise we recommend Vim as an alternative)
  2. Ranger - A directory / file explorer providing an easier way to find files via the terminal - sort of like Windows Explorer for the console.
  3. Ncdu - Must-have tool that easily figures out how much space is on a system, and where big files / directories are lurking - kinda like WinDirTree for Windows
  4. Bat - a Linux "cat" command alternative, provides syntax highlighting and enumeration in a clean, efficient interface - we love this, and think you would too
  5. MTR-tiny - A package that combines ping and traceroute into a single tool with superpowers to isolate networking issues
  6. Lnav - As discussed above, a tool to explore and decipher all of those pesky cryptic log files you need to review in order to troubleshoot an issue
  7. Mulittail - View multiple log files at a time via the console - often helps to uncover what's going on in a borked OS
  8. Tig - A terminal based Git client (for the crafty developers among you)
  9. Rtorrent - terminal based BitTorrent client - for all that (ahem) legal downloading you do  ;-)
  10. Ned - because sed sucks - yes it does 
  11. MyCli - Console client for MySql / MariaDB databases that does auto-completion and syntax highlighting  - As most services with a web interface have a database in the back-end
  12. Glances - Console (and web) based server monitoring tool  (like top on steroids) - See what's going on "at a glance", we use this often to monitor web services
  13. Taskwarrior - Manage ToDo / task lists from the console - We like our Markdown GUI clients for individual lists, but this is mighty useful when you don't have a GUI
  14. Calcurse - Calendar and appointment tool for the console - Again, for when you don't have a GUI to run Google Chrome / Firefox etc.
  15. Htop - Top clone with syntax highlighting and mouse support - The go-to must-have command line tool to understand what a Linux system is doing
Games:
  • Nudoku - Sudoko for the console / terminal (available also for the Mac via homebrew) - it's not all about work
  • Ninvaders - Play space invaders via the console (available also for the Mac via homebrew) - Because 80's Atari games never ever get old...
  • Bastet - A Tetris clone for the console - C'mon it's Tetris, for the console ... how isn't this cool?