Command Line Overview

Unix was not designed to stop people from doing stupid things, because that would also stop them from doing clever things. — Doug Gwyn

• Knowledge of the Command Line is essential!
  • Necessary to compile programs from source (much easier than loading into IntelliJ or other IDE)
  • Necessary when working with remote machines (i.e., servers and clouds)
  • Compact, unambiguous, way to represent instructions for doing things
  • Allows complex tasks to be automated (almost anything can be scripted)
  • Basically, it is a powerful tool for scaling your activities to many things!

   

• Unix survives because of several key design decisions
  • The Unix Philosophy as summarized by Doug McIlroy
    • Write programs that do one thing and do it well
    • Write programs to work together
    • Write programs to handle text streams, because that is a universal interface
  • Basically, everything works via abstractions!
    • For example: everything is treated as a "file": files, network data, the keyboard and mouse, even the output of commands
    • Command output can be "piped" in as another commands input to make very concise scripts (programs)
  • From the Ubuntu web site:
    "As any Linux user knows, it's the command line terminal where the magic happens. It's perfect for file management, development, remote administration and a thousand other tasks."

 

• Useful Commands
  

  ls	list contents of a directory
  cd	change the working directory
  cp	copy files
  mv	move files
  rm	remove files (be careful — no UNDO!)
  mkdir	make a directory
  grep	look for strings in a file matching a given criteria
  diff	report differences between files
  find	find files matching a given criteria
  sort	sort data based on variety of criteria
  tar	compress/uncompress files
  man	help page for a command

  Using arguments, wildcards, and expansions are powerful ways to make these commands target specific types of data

• Working with Files
  

  cat	output the contents of a file
  less	page through a file
  head	show the first lines in a file
  tail	show the last lines in a file
  nano	simple in shell text editor
  vi	complex in shell text editor
  emacs	complex in shell text editor

 

• "Unix" Command Line Options
  • Use a Virtual Machine (VM): VirtualBox (free), VMware (Duke has a site license)
  • Boot from CD or USB drive (knoppix)
  • Dual boot your machine
  • Directly on your machine (can be dangerous): Linux, Mac, Cygwin on Windows, Ubuntu on Windows (now with Copy/Paste)!

   

• Working with the Filesystem
  • File permissions
  • File types
  • What is sudo?
    Never type "rm -r *" or especially "sudo rm -r /*"

Resources

• Basics of the Unix Philosophy by Eric S. Raymond
• Basic Command Line Reference (based on Git Bash for Windows)
• More complete Command Line Reference
• Learning the Shell by William Shotts
• What Should Be Configurable? by Eric S. Raymond