Which command would you use to modify an existing group?

The command used to modify an existing group is "groupmod." This command allows system administrators to change properties of a group, such as its name or group ID (GID). For instance, if you wanted to rename a group, you would use the "groupmod" command followed by the current group name and the new group name as parameters. This makes "groupmod" specifically tailored for the manipulation of group settings within the Linux operating system.

The other commands listed serve different purposes: "useradd" is utilized to add new users, "usermod" is used for modifying existing user accounts (such as changing a username or home directory), and "deluser" is employed to remove a user from the system. Each command is distinct in its functionality, reinforcing the importance of using the correct command for the specific administrative task at hand.