What is a Shebang
What is the Shell
What is the shell
What is the difference between a terminal and a shell
What is the shell prompt
How to use the history (the basics)
How to navigate in an Unix system
How to list files and directories
How to display the content of a file
How to create a file or directory
How to remove a file or directory
How to move or copy a file or directory
What happens when you type $ ls -l *.txt
What do the commands or built-ins cd, pwd, ls do
How to navigate the filesystem
What are the . and .. directories
What is the working directory, how to print it and how to change it
What is the root directory
What is the home directory, and how to go there
What is the difference between the root directory and the home directory of the user root
What are the characteristics of hidden files and how to list them
What does the command cd - do
What do the commands ls, less, file do
How do you use options and arguments with commands
Understand the ls long format and how to display it
What is Emacs
Who is Richard Stallman
How to open and save files
What is a buffer and how to switch from one to the other
How to use the mark and the point to set the region
How to cut and paste lines and regions
How to search forward and backward
How to invoke commands by name
How to undo
How to cancel half-entered commands
How to quit Emacs
What is vi
Who is Bill Joy
How to start and exit vi
What are the command and insert modes, and how to switch from one to the other
How to edit text
How to cut and paste lines
How to search forward and backward
How to undo
How to quit vi
What does the ln command do
What do you find in the most common/important directories
What is a symbolic link
What is a hard link
What is the difference between a hard link and a symbolic link
What do the commands cp, mv, rm, mkdir do
What are wildcards and how do they work
How to use wildcards
What do type, which, help, man commands do
What are the different kinds of commands
What is an alias
When do you use the command help instead of man
How to read a man page
What are man page sections
What are the section numbers for User commands, System calls and Library functions
Common shortcuts for Bash
What does LTS mean
What do the commands chmod, sudo, su, chown, chgrp do
Linux file permissions
How to represent each of the three sets of permissions (owner, group, and other) as a single digit
How to change permissions, owner and group of a file
Why can’t a normal user chown a file
How to run a command with root privileges
How to change user ID or become superuser
How to create a user
How to create a group
How to print real and effective user and group IDs
How to print the groups a user is in
How to print the effective userid
How to display a line of text
How to concatenate files and print on the standard output
How to reverse a string
How to remove sections from each line of files
What is the /etc/passwd file and what is its format
What is the /etc/shadow file and what is its format
What do the commands head, tail, find, wc, sort, uniq, grep, tr do
How to redirect standard output to a file
How to get standard input from a file instead of the keyboard
How to send the output from one program to the input of another program
How to combine commands and filters with redirections
What are special characters
Understand what do the white spaces, single quotes, double quotes, backslash, comment, pipe, command separator, tilde and how and when to use them
What are the /etc/profile file and the /etc/profile.d directory
What is the ~/.bashrc file
What is the difference between a local and a global variable
What is a reserved variable
How to create, update and delete shell variables
What are the roles of the following reserved variables: HOME, PATH, PS1
What are special parameters
What is the special parameter $??
What is expansion and how to use them
What is the difference between single and double quotes and how to use them properly
How to do command substitution with $() and backticks
How to perform arithmetic operations with the shell
How to create an alias
How to list aliases
How to temporarily disable an alias
How to execute commands from a file in the current shell
CMD CHALLENGE is a pretty cool game challenging you on Bash skills. Everything is done via the command line and the questions are becoming increasingly complicated. It’s a good training to improve your command line skills!