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Learn command line

Please follow and complete the free online Command Line Crash Course tutorial or Codecademy's Learn the Command Line. These are helpful tutorials. Each "chapter" focuses on a command. Type the commands you see in the Do This section, and read the You Learned This section. Move on to the next chapter. You should be able to go through these in a couple of hours.

Q1. Cheat Sheet of Commands

Here's a list of items with which you should be familiar:

  • show current working directory path
  • creating a directory
  • deleting a directory
  • creating a file using touch command
  • deleting a file
  • renaming a file
  • listing hidden files
  • copying a file from one directory to another

Make a cheat sheet for yourself: a list of at least ten commands and what they do. (Use the 8 items above and add a couple of your own.)

  • pwd - show current working directory path
  • mkdir - creating a directory
  • rm -r - deleting a directory
  • touch [filename] - creating a file using touch command
  • rm [filename] - deleting a file
  • mv [Path to filename] [Path to new filename] - renaming a file
  • ls -la - listing hidden files
  • cp [Path to file] [New Path] - copying a file from one directory to another
  • grep [regex] * - find all instances of a given regex in current directory
  • env - list all environment variables
  • cat [filename] - display contents of file in current directory to STDOUT
  • less [filename] - view contents of file by page
  • sudo su - switch user to root

Q2. List Files in Unix

What do the following commands do:
ls
ls -a
ls -l
ls -lh
ls -lah
ls -t
ls -Glp

ls - display contents of current directory
ls -a - display all (including hidden) contents of current directory
ls -l - display contents of current directory in long list format
ls -lh - display file/folder sizes of current directory in human readable format
ls -lah - display all contents of current directory in human readable long list format
ls -t - sort contents by last time modified
ls -Glp - display long list without group names and by appending '/' to directory names

Q3. More List Files in Unix

Explore these other ls options and pick 5 of your favorites:

  • ls -Rl - display list of subdirectories contents recursively
  • ls -lX - list sorted by name alphabetically
  • ls -lS - list sorted by file size
  • ls -lah - long list of all files with human readable sizes
  • ls -lt - list sorted by last time modified

Q4. Xargs

What does xargs do? Give an example of how to use it.

xargs will start its own command line and can be used to run commands in parallel by piping input from one command to xargs. In the following example I will use xargs to open all files in the current path that have the .py extension:

find . -name "*.py" | xargs gedit