Let me provide a brief explanation of the functions you've shared:
echo(): This function overrides the built-in echo command. It uses /bin/cat to display the provided arguments as standard input using a "here document" (<< EOC). This function essentially replicates the functionality of the standard echo command but in a more complex way.
whoami(): This function replicates the whoami command by using /usr/bin/id -u -n to display the current user's username.
pwd(): This function replicates the pwd (print working directory) command by echoing the value of the PWD environment variable.
These functions can be added to your .bash_profile file to customize your shell environment. However, be cautious when overriding built-in commands like echo, as it can lead to confusion and unexpected behavior when working with scripts or other tools that rely on these commands.