Together, the /usr/sbin/useradd command and /etc/skel directory (both are easy to setup and use) provide a way to assure new users are added on your LFS system with the same beginning settings for things like PATH, keyboard processing and environmental variables. Using these two facilities makes it easier to assure this initial state for each new user.
The /etc/skel directory holds copies of various initialization and other files that may be copied to the new user's home directory when the /usr/sbin/useradd program adds the new user.
The useradd program uses a collection of default values kept in /etc/default/useradd, if it exists. If the file does not exist, then it uses some internal defaults. You can see the default values by running /usr/sbin/useradd -D.
To change these values to something new, create a base /etc/default/useradd file with the same values as the output of /usr/sbin/useradd -D. Here is a sample.
# Begin /etc/default/useradd GROUP=100 HOME=/home INACTIVE=-1 EXPIRE= SHELL= SKEL=/etc/skel # End /etc/default/useradd
The only thing missing from the file is a default shell. Add that by running:
/usr/sbin/useradd -D -s/bin/bash
This will set the SHELL= line to SHELL=/bin/bash.
Useradd has many parameters that can be set in the /etc/default/useradd file.
For more information see man useradd.
To get started, create an /etc/skel directory and make sure it is writable only by the system administrator, usually root. Creating the directory as root is the best way to go.
The mode of any files from this part of the book that you put in /etc/skel should be writable only by the owner. Also, since there is no telling what kind of sensitive information a user may eventually place in their copy of these files, you should make them unreadable by "group" and "other".
You can also put other files in /etc/skel and different permissions may be needed for them.
Decide which initialization files should be provided in every (or most) new user's home directory. The decisions you make will affect what you do in the next three sections, /etc/inputrc, The Bash Shell Startup Files and /etc/vimrc, ~/.vimrc. Some or all of those files will be useful for root, any already-existing users, and new users.
The files from those sections that you might want to place in /etc/skel include .inputrc, .bash_profile, .bashrc, .bash_logout, .dircolors, and .vimrc. If you are unsure which of these should be placed there, just continue to the following sections, read each section and any references provided, and then make your decision.
You will run a slightly modified set of commands for files which are placed in /etc/skel. Each section will remind you of this. In brief, the book's commands have been written for files not added to /etc/skel and just send the results to the user's home directory. If the file is going to be in /etc/skel, change the book's command(s) to send output there instead and then just copy the file from /etc/skel to the appropriate directories, like /etc, ~ or the home directory of any other user already in the system.
When Adding a User
When adding a new user with useradd, use the -m parameter, which tells useradd to create the user's home directory and copy files from /etc/skel (can be overridden) to the new user's home directory. For example:
useradd -m jwrober