User Permission Management in Linux/Ubuntu
To list
To list all local users you can use:
cut -d: -f1 /etc/passwd
To add
To add a new user you can use:
sudo adduser new_username
or:
sudo useradd new_username
To remove/delete
To remove/delete a user, first you can use:
sudo userdel username
Then you may want to delete the home directory for the deleted user account :
sudo rm -r /home/username
add new user in linux
sudo adduser new_username
To modify
To modify the username of a user:
usermod -l new_username old_username
To change the password for a user:
sudo passwd username
To change the shell for a user:
sudo chsh username
To change the details for a user (for example real name):
sudo chfn username
To add a user to the sudo group:
adduser username sudo
or
usermod -aG sudo username
And, of course, see also: man adduser, man useradd, man userdel... and so on.