将新用户“jack”添加到Ubuntu 20.04操作系统：

$ sudo adduser jack
Adding user `jack' ...  
Adding new group `jack' (1001) ... 
Adding new user `jack' (1001) with group `jack' ...
Creating home directory `/home/jack' ...
Copying files from `/etc/skel' ...
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
Changing the user information for jack
Enter the new value, or press ENTER for the default
        Full Name []: 
        Room Number []: 
        Work Phone []: 
        Home Phone []: 
        Other []: 
Is the information correct? [Y/n] y

（可选）根据系统和环境，我们可能需要将用户添加到特定组。
例如，以下命令将添加用户jack到组cdrom：

$ sudo usermod -aG cdrom jack

• （可选）检索用户和组信息以确认用户成功创建：

$ id jack
uid=1001(jack) gid=1001(jack) groups=1001(jack),24(cdrom)