Skip to main content

Users and Groups

Updated Mar 27, 2021 ·

Tasks​

  1. Make sure new users' passwords are 6-characters minimum and wth a maximum validity of 90 days.
  2. Ensure that an empty file newfil is created on the home directory when new users are created.
  3. Create users ted, barney, robin, lily, and marshall.
  4. Set passwords for ted, barney, and robin to 'password'
  5. Disable passwords for lily and marshall.
  6. Create groups teamted and teamrobin and assign them the users:
    • TeamTed: ted, barney, marshall
    • TeamRobin: robin, lily

Solution​

1. Set password length and validity​

Make sure new users' passwords are 6-characters minimum and wth a maximum validity of 90 days.

sudo sed -i 's/^PASS_MIN_LEN.*/PASS_MIN_LEN 6/' /etc/login.defs
sudo sed -i 's/^PASS_MAX_DAYS.*/PASS_MAX_DAYS 90/' /etc/login.defs

2. Auto-create a file on new home directories​

Ensure that an empty file newfil is created on the home directory when new users are created. Create the file in the /etc/skel directory:

sudo touch /etc/skel/newfil

Check:

$ ll /etc/skel/
total 20
drwxr-xr-x  2 root root 4096 Jun 16 06:52 ./
drwxr-xr-x 75 root root 4096 Jun 29 11:30 ../
-rw-r--r--  1 root root  220 Jan  7  2022 .bash_logout
-rw-r--r--  1 root root 3771 Jan  7  2022 .bashrc
-rw-r--r--  1 root root  807 Jan  7  2022 .profile 
-rw-r--r--  1 root root  807 Jan  7  2022 newfil

3. Create users​

Create users ted, barney, robin, lily, and marshall.

sudo useradd ted
sudo passwd ted

sudo useradd barney
sudo passwd barney

sudo useradd robin
sudo passwd robin

sudo useradd lily
sudo passwd lily

sudo useradd marshall 
sudo passwd marshall

4. Set passwords for specific users​

Set passwords for ted, barney, and robin to 'password'

echo "ted:password" | sudo chpasswd
echo "barney:password" | sudo chpasswd
echo "robin:password" | sudo chpasswd

5. Disable passwords for specific users​

Disable passwords for lily and marshall.

sudo usermod -s /sbin/nologin lily
sudo usermod -s /sbin/nologin marshall

Now, when you try to login, it will automatically fail.

$ su - lily
Password:
su: Authentication failure

6. Create groups and assign users​

Create groups teamted and teamrobin and assign them the users:

  • teamted: ted, barney, marshall
  • teamrobin: robin, lily

Create the groups:

sudo groupadd teamted
sudo groupadd teamrobin

Add users to teamted:

sudo usermod -aG teamted ted
sudo usermod -aG teamted barney
sudo usermod -aG teamted marshall

Add users to teamrobin:

sudo usermod -aG teamrobin robin
sudo usermod -aG teamrobin lily