Working on a Mac OS X or Linux system really helps your productivity. Basically you just do the stuff you are supposed to do, without being distracted by a graphical interface showing you several options to choose from, at each click or navigation step. That's the point of using Command-Line Interface tools.

Like any other tool, you have to use these CLI tools everyday to get the most benefit from them, and for the process to become natural.

Here is a selection from the always growing list of tools I use daily:

git

The client for code version control on Github or alternative platforms, and for cloning repositories of stuff I may need to test.

git clone https://github.com/someuser/somereposirory.git

More info: https://git-scm.com

mycli

A client for interacting with MySQL databases.

mycli -h localhost -u somedbuser somedb

More info: http://mycli.net

cURL

Useful for quickly testing HTTP calls to API endpoints such as api.github.com.

curl https://api.github.com/users/{someuser}

More info: https://curl.haxx.se

Drush

The CLI for Drupal's administrative tasks.

drush help

More info: http://drush.org / https://drushcommands.com

django-admin

The CLI for Django's administrative tasks.

django-admin help --commands

More info: https://docs.djangoproject.com

Firebase CLI

A set of tools for Firebase services (now part of Google's Cloud platform). Useful in my case for deploying static sites to Firebase Hosting.

firebase deploy --help

More info: https://firebase.google.com/docs/hosting

doctl

The CLI for accessing the DigitalOcean API.

doctl compute droplet list

More info: https://github.com/digitalocean/doctl

AWS CLI

The CLI for managing AWS services.

aws configure
...

aws ec2 describe-instances --output table --region us-west-2
...

More info: https://aws.amazon.com/documentation/cli