## https://www.techduck.ca/pi-to-newname.txt
## Changing the default admin username on the rpi4 and rpi3b.
## No other rpi versions were tested.

## If this rpi is connecting to the internet, this is not a bad idea.
## At least change the password!

## Please see the "Terms Of Service and Disclaimer" 
## at https://www.techduck.ca/td-ToS-Disclaimer.html

## Note: It is bad policy to follow instructions found online.
## Read man pages: grep egrep sed groupmod usermod subgid subuid passwd
## and understand what you are about to do.
## If it did not work, so sorry - beyond the scope of this document.
## ..it can be fixed.  Read those man pages.  Still stuck?
## Run "history | tail -n 80" and paste output into the body of a
## non-html email and send it to info at techduck.ca - will have a look.

## So having decided to do this, be sure to substitute "newname" with 
## your new admin username :^)  If Auto Login is set, change that using
## main menu -> Preferences -> Raspberry Pi Configuration

## The usermod caveat that pi can not run any processes or it will fail
## so the root account needs a password to run the commands below.
# sudo passwd root

## Now logout for the last time as pi. When login screen reappears,
## type Ctrl-Alt-F1 to get a terminal and log in _there_ as root.

## Now check that pi owns no running processes. 
# ps -U pi 
## Any process still owned by pi must be stopped.
# pkill -U pi

## Check the state of things before, during and after.
# cat /etc/subgid
# cat /etc/subuid
# ls -l /home/pi
# ls -l /home/newname
# grep pi /etc/group
# grep newname /etc/group
# cat /etc/sudoers.d/010_pi-nopasswd /etc/sudoers.d/010_newname-nopasswd

## Replace the pi login name with the uid in subgid and subuid.
# sed -i 's/pi/1000/' /etc/subuid 
# sed -i 's/pi/1000/' /etc/subgid

## Now run these commands in this order. Checking as above never hurts.
# groupmod -n newname pi
# usermod -l newname pi
# usermod -m -d /home/newname newname

## This new user needs to have admin permission. So set this up.
# mv /etc/sudoers.d/010_pi-nopasswd /etc/sudoers.d/010_newname-nopasswd
# sed -i 's/pi/newname/' /etc/sudoers.d/010_newname-nopasswd

## Check state of things and if it looks good, set a password 
## for the new user.
# passwd newname

## Now enter Ctrl-Alt-F7 and login to the GUI as the new user.
##