'\" t
.\"     Title: shadow
.\"    Author: Julianne Frances Haugh
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 27/06/2025
.\"    Manual: File Formats and Configuration Files
.\"    Source: shadow-utils 4.18.0
.\"  Language: Italian
.\"
.TH "SHADOW" "5" "27/06/2025" "shadow\-utils 4\&.18\&.0" "File Formats and Configuration"
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.SH "NOME"
shadow \- file delle password shadow
.SH "DESCRIZIONE"
.PP
shadow
is a file which contains the password information for the system\*(Aqs accounts and optional aging information\&.
.PP
Questo file non deve essere leggibile dagli utenti normali se si vuole mantenere la sicurezza sulle password\&.
.PP
Each line of this file contains 9 fields, separated by colons (\(Fo:\(Fc), in the following order:
.PP
\fBlogin name\fR
.RS 4
It must be a valid account name, which exists on the system\&.
.RE
.PP
\fBencrypted password\fR
.RS 4
If the password field is empty, the user can log in without a password\&. However, some applications that read the
/etc/shadow
file might block access if the password field is empty\&.
.sp
If the password field begins with an exclamation mark
\fI!\fR, the password is locked\&. The remaining characters on the line represent the password field before the password was locked\&.
.sp
Refer to
\fBcrypt\fR(3)
for details on how this string is interpreted\&.
.sp
If the password field contains a string that is not a valid result of
\fBcrypt\fR(3), for instance ! or *, the user cannot use a UNIX password to log in\&. However, the user may log in the system by other means\&.
.RE
.PP
\fBdate of last password change\fR
.RS 4
The date of the last password change, expressed as the number of days since 1970\-01\-01 00:00:00 UTC\&.
.sp
The value 0 indicates that the user must change their password the next time they log in to the system\&.
.sp
Un campo vuoto implica che la scadenza della password \(`e disabilitata\&.
.RE
.PP
\fBminimum password age\fR
.RS 4
The minimum password age is the number of days the user must wait before they can change their password again\&.
.sp
An empty field and value 0 mean that there is no minimum password age\&.
.RE
.PP
\fBmaximum password age\fR
.RS 4
The maximum password age is the number of days after which the user must change their password\&.
.sp
After this number of days has elapsed, the password may still be valid\&. The user is prompted to change their password at the next login\&.
.sp
Un campo vuoto indica che non ci sono una et\(`a massima password, un periodo di avviso e nessun periodo di inattivit\(`a (vedere oltre)\&.
.sp
Se l\*(Aqet\(`a massima password \(`e minore dell\*(Aqet\(`a minima password, l\*(Aqutente non pu\(`o cambiare la propria password\&.
.RE
.PP
\fBpassword warning period\fR
.RS 4
The number of days before a password expires (see the maximum password age above) during which the user is warned\&.
.sp
An empty field and value 0 mean that there is no password warning period\&.
.RE
.PP
\fBpassword inactivity period\fR
.RS 4
The number of days after a password expires (see the maximum password age above) during which the password is still accepted, and the user must update their password at the next login\&.
.sp
After the password expires and the password inactivity period elapses, the user cannot log in and must contact their administrator\&.
.sp
An empty string means that no inactivity period is enforced\&.
.RE
.PP
\fBaccount expiration date\fR
.RS 4
The date when the account expires, expressed as the number of days since 1970\-01\-01\&.
.sp
Note that account expiration differs from password expiration\&. Account expiration prevents the user from logging in, whereas password expiration only prevents users from logging in with their password\&.
.sp
An empty field means that the account never expires\&.
.sp
The value 0 should not be used, as it is interpreted either as an account with no expiration or as an expiration date of 1970\-01\-01\&.
.RE
.PP
\fBreserved field\fR
.RS 4
Questo campo \(`e riservato per uso futuro\&.
.RE
.SH "FILE"
.PP
/etc/passwd
.RS 4
Informazioni sugli account utente\&.
.RE
.PP
/etc/shadow
.RS 4
Informazioni sicure sugli account utente\&.
.RE
.PP
/etc/shadow\-
.RS 4
Copia di backup per /etc/shadow\&.
.sp
Notare che questo file viene usato dagli strumenti del pacchetto shadow, ma non da tutti gli strumenti per la gestione di utenti e password\&.
.RE
.SH "VEDERE ANCHE"
.PP
\fBchage\fR(1),
\fBlogin\fR(1),
\fBpasswd\fR(1),
\fBpasswd\fR(5),
\fBpwck\fR(8),
\fBpwconv\fR(8),
\fBpwunconv\fR(8),
\fBsu\fR(1),
\fBsulogin\fR(8)\&.