The purpose of a .bashrc file is to provide a place where you can set up variables, functions and aliases, define your (PS1) prompt and define other settings.

Set environment variable

Set a new variable, add a new line at the end of .bashrc and add

export VARNAME="var_value"

Add new value to a existing environment variable, such as PATH

export PATH="new_value":${PATH}

Or define a new variable first, then use the new variable.

export VARNAME="var_value"

export PATH=${VARNAME}:${PATH}

Set alias

alias examples

alias apt-get='sudo apt-get'

alias ls='ls --color=auto'

Take effect

Make changes in .bashrc immediately effective.

$ source ~/.bashrc