shadow(4)

shadow -- shadow password file

Description

/etc/shadow is an access-restricted ASCII system file that contains an entry for each user on the system. The fields within each entry are separated by colons; each entry is separated from the next by a new-line. Unlike the /etc/passwd file, /etc/shadow does not have general read permission.

Here are the fields in /etc/shadow:

``login_name'': The name by which a user identifies himself or herself when logging in.
``password'': A 13-character encrypted password for the user, a ``lock'' string to indicate the login is not accessible, or no string to show that there is no password for the login.
``lastchanged'': The number of days between January 1, 1970, and the date that the password was last modified.
``minimum'': The minimum number of days required between password changes.
``maximum'': The maximum number of days the password is valid.
``warn'': The number of days before password expires that the user is warned.
``inactive'': The number of days of inactivity allowed for that user.
``expire'': An absolute date specifying when the login may no longer be used.
``flag'': A character identifying a password generator.

The encrypted password consists of 13 characters chosen from a 64-character alphabet (., /, 0-9, A-Z, a-z).

To update this file, use the passwd, useradd, usermod, or userdel command.

Files

/etc/shadow

References

getspent(3G), login(1), passwd(1), passwd(4), putspent(3C), useradd(1M), userdel(1M), usermod(1M)