LFCS User and Group Management Practice Test 7 — 15 Questions

Question 1

A system administrator needs to create a shared group 'projectx' and add existing users 'bob' and 'carol' to it. The users need to collaborate on files in a directory /projectx. What is the correct sequence of commands to set up the group and ensure new files created in /projectx are automatically owned by the group 'projectx'?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

groupadd projectx; usermod -aG projectx bob; usermod -aG projectx carol; chmod g+s /projectx. It uses `groupadd` to create the group, `usermod -aG` to append users to the group without removing them from other groups, and `chmod g+s` to set the setgid bit on the directory. The setgid bit ensures that new files created in /projectx inherit the group ownership of the directory (projectx), enabling collaboration.

Answer

groupadd projectx; usermod -G projectx bob carol; chmod 2770 /projectx

Answer

addgroup projectx; adduser bob projectx; adduser carol projectx; chmod u+s /projectx

Answer

groupadd projectx; usermod -G projectx bob; usermod -G projectx carol; chmod g+s /projectx

Question 2

A security policy requires that all users in the 'admin' group must have a umask of 027 set automatically upon login. An administrator adds 'umask 027' to /etc/profile. However, users report that the umask is still 022. What is a likely cause?

Accepted Answer

The umask in /etc/profile is overridden by user-specific .bash_profile or .bashrc files.. User-specific shell configuration files (like ~/.bash_profile, ~/.bash_login, or ~/.profile for login shells, and ~/.bashrc for interactive non-login shells) are sourced after /etc/profile. These files can override the system-wide umask setting with a user-defined value, such as the default 022. Since the administrator only modified /etc/profile, any existing user-specific umask command in their personal dotfiles will take precedence.

Answer

The umask command in /etc/profile has a syntax error that is silently ignored.

Answer

The admin placed the umask command after the call to /etc/bash.bashrc which resets it.

Answer

The admin forgot to run 'source /etc/profile' on each user's session.

Question 3

An administrator wants to change the primary group of user 'jane' from 'staff' to 'developers'. Which command accomplishes this?

Accepted Answer

usermod -g developers jane. The `usermod -g` command changes the primary group of a user. The `-g` option specifies the new primary group (by name or GID), and the user's existing primary group is replaced. This directly accomplishes the administrator's goal of changing jane's primary group from 'staff' to 'developers'.

Answer

usermod -G developers jane

Answer

groupmod -g developers jane

Answer

chgrp developers jane

Question 4

Which command will display all groups a specific user belongs to, including both primary and supplementary groups?

Accepted Answer

groups username. The 'groups' command is the standard utility to list all group memberships for a given user, showing both the primary group (from /etc/passwd) and any supplementary groups (from /etc/group). It queries the system's group database directly, making it the correct and simplest choice for this task.

Answer

cat /etc/passwd | grep username

Answer

id -g username

Answer

grep username /etc/group

Question 5

Which TWO commands can be used to display the group membership of a user? (Choose two.)

Accepted Answer

id -Gn username. Option A, 'id -Gn username', is correct because the -G flag lists all group IDs the user belongs to and -n converts those GIDs to group names, so it prints every group name the user is a member of. Option D, 'groups username', is correct because the groups command prints the group names that the specified user belongs to, directly showing group membership. Option B, 'cat /etc/passwd | grep username', only shows the user's passwd entry, which contains the primary GID but not supplementary group memberships. Option C, 'id -g username', prints only the primary group ID (or name with -n), not the full set of groups. Option E, 'grep username /etc/group', only finds groups where the username appears in the member list and misses the user's primary group, so it does not reliably display complete group membership.

Answer

cat /etc/passwd | grep username

Answer

id -g username

Answer

grep username /etc/group

Question 6

Which command adds an existing user to a supplementary group without removing the user from other groups?

Accepted Answer

usermod -aG groupname username. The correct command is `usermod -aG groupname username`. The `-a` option (append) combined with `-G` (supplementary groups) adds the user to the specified group without affecting existing supplementary group memberships. Option A (`groupmod -a`) is incorrect because `groupmod` modifies group attributes, not user membership. Option B (`-A`) is not a valid `usermod` option. Option D (`-g`) changes the user's primary group, not supplementary groups.

Answer

groupmod -a username groupname

Answer

usermod -A groupname username

Answer

usermod -g groupname username

Question 7

A user must change their password at next login per security policy. The admin wants to expire the password immediately. Which command accomplishes this?

Accepted Answer

chage -d 0 username. The chage -d 0 username command sets the 'last password change' date to 0 (January 1, 1970), which forces the user to change their password at the next login. This is the standard Linux method to immediately expire a user's password without disabling the account.

Answer

passwd -f username

Answer

usermod -p '' username

Answer

chage -M 90 username

Question 8

After deleting user 'alice', the system administrator wants to also remove the home directory and mail spool. Which command should be used?

Accepted Answer

userdel -r alice. The correct option is B, userdel -r alice. The -r flag removes the user's home directory and mail spool, along with the user account. This is the standard flag for removing user data along with the account.

Answer

userdel -Z alice

Answer

userdel -f alice

Answer

userdel --remove alice

Question 9

Which file stores the encrypted password (or password hash) for user accounts?

Accepted Answer

/etc/shadow. /etc/shadow is correct because it stores encrypted password hashes for user accounts, along with password aging information. It is readable only by root to prevent unauthorized access to password hashes. The /etc/passwd file historically stored passwords but now only contains user account information, with the password field replaced by an 'x' indicating the hash is in /etc/shadow.

Answer

/etc/group

Answer

/etc/passwd

Answer

/etc/gshadow

Question 10

Which THREE of the following statements about the user private group (UPG) scheme are true?

Accepted Answer

It is the default scheme in Red Hat-based distributions.. Options A, D, and E are true. A: It is the default scheme in Red Hat-based distributions. D: It ensures that new files have a default group of the user's private group. E: Each user is assigned a unique group with the same name as the username. B is false because umask 0027 gives group read permission, not denies it. C is false because the primary group is the user's private group, not a system group.

Answer

The umask 0027 ensures files created are NOT readable by the group.

Answer

The primary group of a user is a system group with GID less than 1000.

Question 11

You are managing a Linux server that hosts a shared project directory /projects/alpha, owned by the group 'alpha' (GID 2001). The directory has permissions 2770 (setgid, rwx for owner and group, no access for others). User 'jane' (UID 1501) has a primary group 'staff' (GID 1001) and is not in the 'alpha' group. She reports being unable to list or modify files in /projects/alpha. You need to give her access as a member of the 'alpha' group without changing her primary group. Which command sequence should you use?

Accepted Answer

usermod -aG alpha jane. The command `usermod -aG alpha jane` appends jane to the supplementary group 'alpha' without altering her primary group 'staff'. Because /projects/alpha is group-owned by alpha with 2770 permissions, group membership grants rwx access, and the setgid bit ensures new files inherit the alpha group. This satisfies the requirement of granting access without changing her primary group.

Answer

usermod -aG alpha jane; usermod -G '' jane; usermod -aG alpha jane

Answer

usermod -g alpha jane

Answer

usermod -G alpha jane

Question 12

A Linux server hosts a shared project workspace at /srv/design. The directory is owned by root and currently has permissions 0775 with group ownership set to the 'designers' group. A new file was just created inside /srv/design by user 'mira' (a member of designers), and the file's group is showing as 'mira' instead of 'designers'. The team lead wants every NEW file and subdirectory created under /srv/design to automatically inherit the 'designers' group, while leaving existing files untouched. Which command should the administrator run?

Accepted Answer

chmod g+s /srv/design. The setgid bit on a directory is the standard mechanism for group inheritance: any file or subdirectory created inside the directory takes the directory's group as its own group. Using chmod g+s on /srv/design applies this behavior without touching existing files or changing individual user group memberships.

Answer

chgrp -R designers /srv/design

Answer

setfacl -R -m g:designers:rwx /srv/design

Answer

chmod +t /srv/design

Question 13

An administrator is auditing a server and needs to list only the users whose primary group is 'developers'. The system has many users, and the administrator wants a precise, scriptable one-liner that parses /etc/passwd. Which command accomplishes this?

Accepted Answer

getent passwd | awk -F: '$4=="'"$(getent group developers | cut -d: -f3)"'" {print $1}'. The passwd database stores the primary group as a numeric GID in the fourth field, so the reliable approach is to resolve the group name to its GID and compare numerically. Using getent keeps the query consistent with NSS sources such as LDAP or SSSD, which plain file greps would miss.

Answer

grep developers /etc/passwd

Answer

getent passwd | awk -F: '$4=="developers" {print $1}'

Answer

getent group developers

Question 14

A junior administrator needs to add user 'mchen' to the supplementary group 'developers' without removing existing group memberships. Which command should be used?

Accepted Answer

usermod -aG developers mchen. To add a user to a supplementary group while preserving existing memberships, use usermod with the -a (append) and -G (supplementary groups) options. Without -a, the -G option replaces all supplementary groups. This command safely adds the new group without affecting others, ensuring the user retains all necessary access.

Answer

usermod -G developers mchen

Answer

groupmod -a -U mchen developers

Answer

gpasswd -a mchen developers

Question 15

A junior administrator created a user account with the command `useradd -m devuser`. The account was created without a password, and the administrator now wants to set an initial password so the user can log in. Which command should the administrator use to assign a password to the account?

Accepted Answer

passwd devuser. Assigning an initial password to an existing account is done with passwd followed by the username when executed as root. That command prompts interactively for the new secret, hashes it, and writes it to /etc/shadow, immediately enabling authentication. The other commands either expect a pre-hashed string, manage unrelated metadata, or apply only during account creation, so none of them sets a usable password here.

Answer

usermod -p devuser

Answer

chage -p devuser

Answer

useradd -p devuser