Purpose of /etc/passwd- and /etc/shadow- ?

[Dr. Michael J. Chudobiak]

On 01/12/2012 12:05 AM, Joachim Backes wrote:
> Hi all,
>
> adding a new user with "useradd ..." will create two additional files
> never removed:
>
> /etc/passwd- and /etc/shadow-
>
> Question: are these files only created for backup purposes, or is there
> another reason for this?

/etc/passwd is world-readable, and contains the basic account info (id, 
real name, home folder).

/etc/shadow is root-only-readable, and contains the password info.

They are separate to improve security.

They are not backups. Those are the main files for local authentication.

- Mike