NAME

shadow − shadow password file

DESCRIPTION

/etc/shadow is an access-restricted ASCII system file.  The fields for each user entry are separated by colons.  Each user 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:

username The user’s login name (ID). 

password A 13-character encrypted password for the user, a lock string to indicate that 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 Reserved for future use, set to zero.  Currently not used. 

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 commands. 

FILES

/etc/shadow

NOTES

If the /etc/passwd file contains any + entries, similar entries should also exist in this file in order to allow logins for users in the NIS database. 

SEE ALSO

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