linuxexpert-practice-labs/labs/linux-plus/2-2-1-users-and-groups

Linux+ 2.2.1: Users and groups

Reading the account files, a skeleton directory, a user, a group and a service account, and the usermod -G trap.

Before you start

The lab only checks that labuser, labsvc, labgroup and /etc/skel/bin don't exist yet; it doesn't create anything. Write answers to the files in /root/lab-answers/. Don't run the chapter's clean-up step: le-lab reset does it.

Tasks

1. Find the lowest UID that useradd gives a normal user on this system, and write it to /root/lab-answers/1.
2. Add a directory bin to /etc/skel. Then create user labuser with the comment Lab User, shell /bin/bash and a home directory (which should get the bin directory); a group labgroup with labuser as a member; and a system account labsvc with no home directory that can't log in.
3. Add labuser to the administrators' group (wheel on RHEL relatives, sudo on Debian and Ubuntu), then run usermod -G labgroup labuser and see what happens to that membership. Finish with labuser in both groups.

Hints

• /etc/login.defs: UID_MIN, SYS_UID_MAX.
• useradd -m -c -s, groupadd, usermod -aG, useradd -r -M -s /sbin/nologin; id, getent passwd.
• -G without -a replaces the list of supplementary groups.