Explaining The Process - Red Hat ENTERPRISE LINUX 4 System Administration Manual

Chapter 32. Users and Groups

32.2.5. Explaining the Process

The following steps illustrate what happens if the command useradd juan is issued on a system
that has shadow passwords enabled:
1. A new line for juan is created in /etc/passwd. The line has the following characteristics:
• It begins with the username juan.
• There is an x for the password field indicating that the system is using shadow passwords.
• A UID greater than 499 is created. (Under Red Hat Enterprise Linux, UIDs and GIDs below 500
are reserved for system use.)
• A GID greater than 499 is created.
• The optional GECOS information is left blank.
• The home directory for juan is set to /home/juan/.
• The default shell is set to /bin/bash.
2. A new line for juan is created in /etc/shadow. The line has the following characteristics:
• It begins with the username juan.
• Two exclamation points (!!) appear in the password field of the /etc/shadow file, which locks
the account.
Note
If an encrypted password is passed using the -p flag, it is placed in the /etc/
shadow file on the new line for the user.
• The password is set to never expire.
3. A new line for a group named juan is created in /etc/group. A group with the same name
as a user is called a user private group. For more information on user private groups, refer to
Section 32.1.1, "Adding a New
The line created in /etc/group has the following characteristics:
• It begins with the group name juan.
• An x appears in the password field indicating that the system is using shadow group passwords.
• The GID matches the one listed for user juan in /etc/passwd.
4. A new line for a group named juan is created in /etc/gshadow. The line has the following
characteristics:
• It begins with the group name juan.
• An exclamation point (!) appears in the password field of the /etc/gshadow file, which locks
the group.
300
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