To test a glob pattern go over to globtester and play around with creating your own file structure online, it's super easy to get started that way.
If you want to test out a glob pattern in the terminal use echo followed by the pattern, for instance.
echo **/*.js
If I run this within a directory with this structure.
.
├── hello
│ └── index.js
├── index.js
└── test.sh
I'll get back the following if you're running bash 4 with globstar enabled.
hello/index.js index.js
If you're running an older version of bash or globstar is not enabled. You might just return this.
hello/index.js
Check if you can enable glob support, run this command.
shopt -s globstar
If nothing happens your good, you can now run free and glob till your hearts content`. If you get an error that looks something like this then it may be time for you to update bash.
bash: shopt: globstar: invalid shell option name
Use brew to install bash, if you don't have it grab it here.
First off it's always a good sanity-check to see what version of bash your running before you start.
bash --version
Install bash with this command
brew update && brew install bash
This line will append the /etc/shells file with the new shell path.
sudo bash -c 'echo /usr/local/bin/bash >> /etc/shells'
Then your going to want to change to the new shell.
chsh -s /usr/local/bin/bash
Now you have to quit the terminal and open it back up again. If you check the version it should show something updated.
bash --version
To enable glob support run the following.
shopt -s globstar
Additional Help
This guide is perfect. Thank you, @reggi!