useradd

In creating the account for testuser, the useradd command performs several actions:

• Reads the /etc/login.defs file to get default values to use when creating accounts.
• Checks command-line parameters to find out which default values to override.
• Creates a new user entry in the /etc/passwd and /etc/shadow files based on the default values and command-line parameters.
• Creates any new group entries in the /etc/group file.
• Creates a home directory based on the user’s name and places it in the /home directory.
• Copies any files located within the /etc/skel directory to the new home directory. This usually includes login and application start-up scripts.

Futher info of /etc/skell  :http://www.linfo.org/etc_skel.html