Computer Science
SHADOW(5) SHADOW(5)
NAME
shadow - encrypted password file
DESCRIPTION
shadow contains the encrypted password information for
user's accounts and optional the password aging informa-
tion. Included is
Login name
Encrypted password
Days since Jan 1, 1970 that password was last changed
Days before password may be changed
Days after which password must be changed
Days before password is to expire that user is warned
Days after password expires that account is disabled
Days since Jan 1, 1970 that account is disabled
A reserved field
The password field must be filled. The encryped password
consists of 13 to 24 characters from the 64 character
alphabet a thru z, A thru Z, 0 thru 9, . and /. Refer to
crypt(3) for details on how this string is interpreted.
The date of the last password change is given as the num-
ber of days since Jan 1, 1970. The password may not be
changed again until the proper number of days have passed,
and must be changed after the maximum number of days. If
the minimum number of days required is greater than the
maximum number of day allowed, this password may not be
changed by the user.
An account is considered to be inactive and is disabled if
the password is not changed within the specified number of
days after the password expires. An account will also be
disabled on the specified day regardless of other password
expiration information.
This information supercedes any password or password age
information present in /etc/passwd.
This file must not be readable by regular users if pass-
word security is to be maintained.
FILES
/etc/passwd - user account information
/etc/shadow - encrypted user passwords
SEE ALSO
chage(1), login(1), passwd(1), su(1), sulogin(8),
shadow(3), passwd(5), pwconv(8), pwunconv(8)
AUTHOR
Julianne Frances Haugh (jfh@tab.com)
1
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