How can I get the current user's username in Bash?

On the command line, enter

whoami

or

echo "$USER"

To save these values to a variable, do

myvariable=$(whoami)

or

myvariable=$USER

Of course, you don't need to make a variable since that is what the $USER variable is for.

An alternative to whoami is id -u -n.

id -u will return the user id (e.g. 0 for root).

Use the standard Unix/Linux/BSD/MacOS command logname to retrieve the logged in user. This ignores the environment as well as sudo, as these are unreliable reporters. It will always print the logged in user's name and then exit. This command has been around since about 1981.

My-Mac:~ devin$ logname
devin
My-Mac:~ devin$ sudo logname
Password:
devin
My-Mac:~ devin$ sudo su -
My-Mac:~ root# logname
devin
My-Mac:~ root# echo $USER
root