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Both files /etc/shadow and /etc/passwd seem to be the same, they just report some information about accounts. What is the difference between them?

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Short answer:

passwd stores general user info and shadow stores user passwd info.

Somewhat longer answer:

passwd is the file where the user information (like username, user ID, group ID, location of home directory, login shell, ...) is stored when a new user is created.

shadow is the file where important information (like an encrypted form of the password of a user, the day the password expires, whether or not the passwd has to be changed, the minimum and maximum time between password changes, ...) is stored when a new user is created.

Some interesting extra info: passwd and shadow

  • Also always useful to have a look at the man files for a command or utility. At the command line simply type: man passwd – kingmilo Nov 28 '17 at 9:22
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/etc/shadow

file stores actual password in encrypted format for user's account with additional properties related to user password i.e. it stores secure user account information. All fields are separated by a colon (:) symbol FOR MORE

/etc/passwd

file stores essential information, which is required during login i.e. user account information. /etc/passwd is a text file, that contains a list of the system's accounts, giving for each account some useful information like user ID, group ID, home directory, shell, etc. FOR MORE

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Traditional Unix systems keep user account information, including one-way encrypted passwords, in a text file called /etc/passwd. As this file is used by many tools (such as ls) to display file ownerships, etc. by matching user id #'s with the user's names, the file needs to be world-readable. Consequentally, this can be somewhat of a security risk.

Another method of storing account information, one that I always use, is with the shadow password format. As with the traditional method, this method stores account information in the /etc/passwd file in a compatible format. However, the password is stored as a single "x" character (ie. not actually stored in this file). A second file, called /etc/shadow, contains encrypted password as well as other information such as account or password expiration values, etc. The /etc/shadow file is readable only by the root account and is therefore less of a security risk.

Details of each file->

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