Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Next, we call three functions: printHeader, checkJava, and checkPython."

A block of code is set as follows:

if [ "${_check_R_req}" = "true" ]; then
 checkR
fi

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

 if [ "$_machine" = "Mac" ]; then
    curl -O $_spark_source
 elif [ "$_machine" = "Linux"]; then
    wget $_spark_source

Any command-line input or output is written as follows:

tar -xvf sbt-1.0.4.tgz
sudo mv sbt-1.0.4/ /opt/scala/

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Go to File | Import appliance; click on the button next to the path selection."

Warnings or important notes appear like this.

Tips and tricks appear like this.