We aim to use our custom bash scripts like other commands in the system just by typing their names. To do so, we need to allocate a folder, write some scripts inside of that folder, and add this folder to the environment variable called $PATH.

Let's go step by step through this process with more explanations.

Creating basic bash scripts

We need to write a few bash scripts to have something that we can add to the system.
Let's create a new folder with name bin in our home directory:

mkdir bin

Inside that folder, let's add two scripts.

bin/hello:

#!/bin/bash
echo "hello $1"

bin/bye:

#!/bin/bash
echo "bye $1"

Making script executable

The scripts have to be executable. To set the execute permissions on our scripts, we need to run this command:

chmod +x *

Adding custom scripts directory to $PATH variable

Now we need to make them visible for the system. We can achieve this by adding our bin folder to the $PATH variable.
$PATH is nothing more than an environment variable that holds a list of different paths to the programs separated by a colon(:)

You can check what is inside by typing in the terminal:

echo $PATH

Lastly, open your .bashrc file. It has to reside in your home directory ~/.bashrc, and add the line below:

export PATH=~/bin:"${PATH}"

Note: If you're using zsh, you can put this line to ~/.zshrc.

Testing

Restart you terminal, and run any of your commands:

hello John

This will print hello John.

As an alternative option to restart, you can source your .bashrc or .zshrc file:

source ~/.bashrc

or

source ~/.zshrc

Next time you start your terminal, your custom bash scripts will be in place so you can use them.