Bash or ZSH add executable

For Bash:

~/.bashrc ~/.bash_profile

For ZSH:

~/.zshrc ~/.zshenv

What is the difference between .bash_profile and .bashrc?

.bash_profile is executed for login shells, while .bashrc is executed for interactive non-login shells.

When you login (type username and password) via console, either sitting at the machine, or remotely via ssh: .bash_profile is executed to configure your shell before the initial command prompt.

But, if you’ve already logged into your machine and open a new terminal window (xterm) then .bashrc is executed before the window command prompt. .bashrc is also run when you start a new bash instance by typing /bin/bash in a terminal.

On OS X, Terminal by default runs a login shell every time, so this is a little different to most other systems, but you can configure that in the preferences.

zsh is extra cool functionality that can be added on your terminal. For zsh .zshrc resembles .bashrc and .zshenv resembles .zshenv.

Add environment variable or exucutable path to .bashrc or .zshrc

Say we like to add type mysql in terminal and /usr/local/opt/mysql@5.7/bin/mysql should be executed. In this case we have to add the path to .bashrc or .zshrc as you prefered one.

To do this in terminal type:

echo 'export PATH="/usr/local/opt/mysql@5.7/bin:$PATH"' >> ~/.bashrc
# For ZSH
echo 'export PATH="/usr/local/opt/mysql@5.7/bin:$PATH"' >> ~/.zshrc

To add environment variable the process is almost the same.

echo 'export NODE_OPTIONS="--max-old-space-size=16384"' >> ~/.bashrc
# For ZSH
echo 'export NODE_OPTIONS="--max-old-space-size=16384"' >> ~/.zshrc

Activate new configuration

You can simply restart the terminal to activate the new configuration. Otherwise run the following command to activate it instantly.

The question can be paraphased as:

How do I reload .bashrc or .zshrc without logging out and back in?

source ~/.bashrc
source ~/.zshrc
# or you can use the shorter version of the command:
. ~/.bashrc
. ~/.zshrc