Manually Creating a New User Account

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Manually Creating a New User Account

• Presented by Carl South

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When creating new user accounts, several steps
must be followed

• Assign username, uid and primary group etc.
• Enter this information into /etc/passwd file
• Assign password to the account
• Create home directory for the user
• Place initialization files into users home dir
• Give the user ownership and access
• Testing the new account

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The /etc/passwd file

• Systems master list of information about users
• Format for each user contains seven fields
• Simply use any text editor to open file and add
  another user
• Example
• namecoded-passwdUIDGIDuser informationhome-di
  rshell
• Note It is always a good idea to save a copy of
  the unedited version so that you can recover from
  any errors

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The /etc/passwd file

• Name - The user name assigned to the user. Most
  user names follow a certain pattern.
  My user name at work is csout0.
• Coded passwd - (Discussed later)
• UID - User ID Each distinct user should have a
  unique user ID
• GID - Group ID Determines the users primary
  group membership
• User Info - Usually contains the users full
  name. Also a comment field.
• Home Directory - Users initial working directory
• Shell - The command interpreter used for the new
  user such as korn, bash, bourne etc.

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The /etc/passwd file (password field)

• There should be an asterisk ( ) placed in this
  field when editing the /etc/passwd file.
• Why? This prevents anyone from using this name
  to log in. Asterisks are not located in the
  target character field for passwords, so it can
  never be matched. Maintains system security if
  you are interrupted while creating the account.
• Passwords should never be assigned while editing
  the /etc/passwd file. The passwd command can be
  used later in the creation of the account.

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The /etc/passwd file

• Example of an entry in the /etc/passwd file
• csout030604222CarlSouth/home/ahvap04/csout0
  /bin/ksh

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Assigning user passwords

• The next step is to assign an initial password
  for the new account.
• Command passwd username
• You will be prompted for the password twice. It
  will not appear on screen.

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Assigning the home directory

• The next step is to create a home directory for
  the new account.
• Command mkdir /home/username
• Note The directory created must match the
  directory name located in the sixth field of the
  new entry in the /etc/passwd file.

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Login initialization files

• Initialization files vary with different shells
  that are used. The bash shell uses .bash, .login
  and .bashrc
• These files are typically located in the
  /etc/skel directory. These files must all be
  placed in the users home directory as part of
  the creation process.

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Changing ownership of home directory

• After creating the users home directory, it is
  important to remember to change the ownership of
  the directory from root to the new user.
• Command chown -R username /home/username
• This command will change the ownership on the
  directory and all the files it contains.

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Testing the account

• After changing ownership, you should log
  completely out and then log back in under the new
  account name using the password that was
  previously assigned.
• Check to see that everything is in working order,
  then switch user (su - root) back to root.

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Testing the account

• Once you are back as root, create a pre-expired
  password for the new account.
• Command passwd -f username
• This will pre-expire the password, forcing the
  user to change it at the next login.

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Automating the process

• A script can be created to automate this process.
  Lets say the script is called make_users. This
  script will make use of a command called useradd,
  which comes with many options.
• Make_users will take one argument on the command
  line that will be the username to be used in
  creating the account.

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Automating the process

• Make_users
• useradd -u 100 -g student -G tty, other -d
  /home/1 -s /bin/ksh -c comment field -k
  /etc/skel -m 1
• Option meanings
• u User ID
• g Primary group
• G Comma-separated list of secondary groups
• d home directory path name
• s shell
• c Full name
• k skeleton directory containing initialization
  files
• m Defines the username

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References

• Essential System Administration, 2nd. Ed..
  OReilly Associates, Inc.
• September 1995. Pg. 144 - 177.
• Unix System Administration. The Seale Group,
  Inc.
• 1996. Training Module Three, Pg. 1 - 17.