EX200 Operate running systems Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  useradd: Creates a new user account

  Why this is correct

  useradd is the standard low-level utility in the shadow-utils package for creating new user accounts. It adds an entry to /etc/passwd and /etc/shadow, optionally creates the user's home directory, and applies defaults from /etc/login.defs and /etc/default/useradd. However, it does not assign a password; an administrator must run passwd afterward. This is the correct tool for the lifecycle stage of account creation.

• ✗

  useradd: Modifies an existing user account

  Why it's wrong here

  useradd cannot modify an existing account; if the username already exists, the command exits with an error such as 'useradd: user 'foo' already exists'. Modifications like changing the home directory, UID, or login shell are performed with usermod, which is specifically designed to alter attributes of already-created accounts. Attempting to use useradd for this purpose is a category error, because useradd only populates new entries.

• ✓

  usermod: Modifies an existing user account

  Why this is correct

  usermod is the correct utility for changing the attributes of an existing user account, such as the login name (-l), home directory (-d), default shell (-s), primary group (-g), supplementary groups (-aG), and account lock state (-L/-U). It directly modifies the relevant lines in /etc/passwd, /etc/shadow, and /etc/group. usermod should be used whenever an account already exists and its properties need to be updated without deleting or recreating it.

• ✗

  usermod: Deletes a user account

  Why it's wrong here

  usermod has no option to delete a user account; its sole purpose is to modify existing accounts. Deleting an account is exclusively the job of userdel, which removes the user's entries from /etc/passwd, /etc/shadow, and /etc/group. Running usermod with deletion in mind would not achieve the goal and could leave the account in an inconsistent state. Therefore, this pairing is incorrect.

• ✓

  userdel: Deletes a user account

  Why this is correct

  userdel is the correct command for removing a user account from the system. It deletes the entries from /etc/passwd, /etc/shadow, and also removes the user's group membership from /etc/group. Using the -r option additionally removes the user's home directory and mail spool. userdel is the counterpart to useradd and completes the account lifecycle.

• ✗

  userdel: Creates a new group

  Why it's wrong here

  userdel is limited to deleting user accounts; it has no functionality to create groups. Group creation is handled by groupadd, which inserts a new entry into /etc/group and /etc/gshadow. The commands are separated by their purpose: userdel works with user entities, while groupadd manages group entities. This pairing confuses two distinct commands from the same suite.

• ✓

  groupadd: Creates a new group

  Why this is correct

  groupadd is the correct tool for creating a new group on the system. It adds an entry to /etc/group and /etc/gshadow, either with an administrator-specified GID using -g or an automatically selected GID from the range defined in /etc/login.defs. It does not add members to the group; membership is assigned later with usermod -aG or gpasswd. This is the standard way to establish a new group.

• ✗

  groupadd: Modifies an existing group

  Why it's wrong here

  groupadd only creates groups; it cannot modify an existing group. If the group already exists, groupadd returns an error indicating the group exists. To modify a group's name, GID, or other attributes, the correct command is groupmod, which updates the /etc/group and /etc/gshadow entries. Thus using groupadd to modify is functionally impossible and incorrect.

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