About git-cal : GitHub-like contributions calendar but on the command-line!
More Information: https://github.com/k4rthik/git-cal

Steps:

1. Launch Terminal by pressing command+space, type terminal and hit Enter key.
2. Run

   ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null

3. Install

   brew install git-cal

Done!

More about git-cal:

• git-cal is a simple script to view commits calendar (similar to github contributions calendar) on command line
• Each block in the graph corresponds to a day and is shaded with one of the 5 possible colors, each representing relative number of commits on that day.
• Option to choose –ascii or –unicode to denote the same instead of the ANSI colors.
• Option to use git config to set options