In this week's lab we used three methods to create user and group accounts. The first method was to directly modify 3 files that are associated with user and group configurations. The second method was to use commands to create users and groups. The third method was by use of the gnome GUI.
In the first method we opened up the /etc/passwd, /etc/shadow, and /etc/group file. We directly edited these files to reflect the information the system needs to correlate the new users with the various group associations. The only purpose I could see using this method other than for training purposes is to possibly troubleshoot issues with creating new users in the more automated method.
In the second method we used the useradd command to create the user. This method is great for mass account creations because it automates many of the functions for you such as creating the home directory, transferring ownership from root to the user, and copying the /etc/skel files. In the event of mass account creation such as company mergers and acquisitions, this method could easily be incorporated into a script and ran against a document with a list of accounts to be created effectively automating the vast majority of the work load for you.
In the third method we used the GUI to add users. This is by far the most simple (conceptually) but labor and time intensive for bulk creation. I would use this method if I needed to create one or two accounts or did not have a comfortable understanding of command lines.