Conventions used in this book

First stop, orientation

I use “Linux” almost exclusively when talking about the operating system surrounding the shell, because

PATH may refer to a variable name, and $PATH definitely refers to a variable value. I will use the latter to avoid any confusion between variables and other things.

[…] means that some of the command output was omitted for brevity. This should be more readable than a bunch of cut, head and tail commands.

Throughout this book, you will see the following typographical conventions that indicate different types of information:

In–line code references will look like this: echo "$SHELL".

Blocks of code look like this:

Shell sessions include:

  • The prompt, which is the string printed before the cursor when starting a new command. It’s set as simply PS1='\$ ' to make it stand out while being short.

  • The command itself.

  • Continuation indicators, which are the strings printed before every line after the first one in a multi–line command. It’s set to the default, PS2='> '.

  • Command standard output and standard error.


  • cat is the first command, spread over three lines and with no terminal output.

  • jq is the second command, followed by its output.

$PS0 is empty. $PS3 and $PS4 are not relevant to this book.

When relevant, shell sessions may include a character to indicate the position of the cursor after running the last command.

Tips and tricks look like this:

mkdir is short for “make directory.”

Warnings look like this:

Use More Quotes™!

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