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HP-UX 11i Version 3: February 2007

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shadow — shadow password file


#include <shadow.h>


The /etc/shadow file is created from the /etc/passwd file by the pwconv command. It is readable only by a privileged user. It can be modified by the passwd, useradd, usermod, and userdel commands. Programs may use the interfaces described in the getspent(3C) manpage to access this information. These functions return a pointer to an spwd structure, which is defined in the <shadow.h> header file.


The /etc/shadow file is an ASCII file consisting of any number of user entries separated by newlines. Each user entry line consists of the following fields separated by colons:

login name

Each login name must match a login name in /etc/passwd. pwconv puts the user entries in /etc/shadow in the same order as the /etc/passwd entries.

encrypted password

The password field of each /etc/passwd entry contains an `x', and the actual encrypted passwords reside in /etc/shadow. The encrypted password field consists of 13 characters chosen from a 64-character set of "digits". The characters used to represent "digits" are . for 0, / for 1, 0 through 9 for 2 through 11, A through Z for 12 through 37, and a through z for 38 through 63. If this field is null, then there is no password and no password is demanded on login. Login can be prevented by entering a character that is not a part of the set of digits (such as *).

last change

The number of days since January 1, 1970 that the password was last modified.

min days

The minimum period in days that must expire before the password can be changed. See also PASSWORD_MINDAYS in security(4) and the passwd -n command in passwd(1).

max days

The maximum number of days for which a password is valid. A user who attempts to login after his password has expired is forced to supply a new one. If min days and max days are both zero, the user is forced to change his password the next time he logs in. If min days is greater than max days, then the password cannot be changed. These restrictions do not apply to the superuser. See also PASSWORD_MAXDAYS in security(4) and the passwd -x command in passwd(1).

warn days

The number of days the user is warned before his password expires. See also PASSWORD_WARNDAYS in security(4) and the passwd -w command in passwd(1).


The maximum number of days of inactivity allowed. This field is set with the -f option of either the useradd or usermod command. If this value is greater than zero, then the account is locked if there have been no logins to the account for at least the specified number of days. If this value is less than or equal to zero, the value is determined by the INACTIVITY_MAXDAYS attribute. See the description of INACTIVITY_MAXDAYS in security(4).


The absolute number of days since Jan 1, 1970 after which the account is no longer valid. A value of zero in this field indicates that the account is locked.


The reserved field is always zero and is reserved for future use.


The /etc/shadow file is not applicable to a system which has been converted to a trusted system.


HP-UX 11i Version 3 is the last release to support trusted systems functionality.



system password file


shadow password file

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