'\" t
.\"     Title: chgpasswd
.\"    Author: Thomas K\(/loczko <kloczek@pld.org.pl>
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 30/07/2026
.\"    Manual: System Management Commands
.\"    Source: shadow-utils 4.20.0
.\"  Language: Italian
.\"
.TH "CHGPASSWD" "8" "30/07/2026" "shadow\-utils 4\&.20\&.0" "System Management Commands"
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.SH "NOME"
chgpasswd \- aggiorna le password di gruppo in modalit\(`a non interattiva
.SH "SINOSSI"
.HP \w'\fBchgpasswd\fR\ 'u
\fBchgpasswd\fR [\fIoptions\fR]
.SH "DESCRIZIONE"
.PP
The
\fBchgpasswd\fR
command reads a list of group name and password pairs from standard input and uses this information to update a set of existing groups\&. Each line is of the format:
.PP
\fIgroup_name\fR:\fIpassword\fR
.PP
By default the supplied password must be in clear\-text, and is encrypted by
\fBchgpasswd\fR\&.
.PP
The default encryption algorithm can be defined for the system with the
\fBENCRYPT_METHOD\fR
variable of
/etc/login\&.defs, and can be overwritten with the
\fB\-e\fR
or
\fB\-c\fR
options\&.
.PP
Questo comando \(`e appositamente pensato per grossi sistemi in cui si abbia la necessit\(`a di creare molti account nello stesso momento\&.
.SH "OPZIONI"
.PP
The options which apply to the
\fBchgpasswd\fR
command are:
.PP
\fB\-c\fR, \fB\-\-crypt\-method\fR
.RS 4
Utilizza il metodo specificato per cifrare le password\&.
.sp
The available methods are
\fISHA256\fR,
\fISHA512\fR,
\fIYESCRYPT\fR
and
\fINONE\fR
if your libc supports these methods\&.
.RE
.PP
\fB\-e\fR, \fB\-\-encrypted\fR
.RS 4
Le password fornite sono in forma cifrata\&.
.RE
.PP
\fB\-h\fR, \fB\-\-help\fR
.RS 4
Mostra un messaggio di aiuto ed esce\&.
.RE
.PP
\fB\-R\fR, \fB\-\-root\fR\ \&\fICHROOT_DIR\fR
.RS 4
Apply changes in the
\fICHROOT_DIR\fR
directory and use the configuration files from the
\fICHROOT_DIR\fR
directory\&. Only absolute paths are supported\&. No SELINUX support\&.
.RE
.PP
\fB\-s\fR, \fB\-\-sha\-rounds\fR
.RS 4
Usa il numero specificato di cicli per cifrare la password\&.
.sp
You can only use this option with crypt method:
\fISHA256\fR
\fISHA512\fR
\fIYESCRYPT\fR
.sp
By default, the number of rounds for SHA256 or SHA512 is defined by the SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS variables in
/etc/login\&.defs\&.
.sp
A minimal value of 1000 and a maximal value of 999,999,999 will be enforced for SHA256 and SHA512\&. The default number of rounds is 5000\&.
.sp
By default, the number of rounds for YESCRYPT is defined by the YESCRYPT_COST_FACTOR in
/etc/login\&.defs\&.
.sp
A minimal value of 1 and a maximal value of 11 will be enforced for YESCRYPT\&. The default number of rounds is 5\&.
.RE
.SH "AVVISI/CAVEAT"
.PP
Ricordarsi di impostare i permessi o umask in modo da prevenire la lettura in chiaro da parte di altri utenti\&.
.PP
Ci si deve accertare che le password e il metodo di cifratura rispettino le norme delle password del sistema\&.
.SH "CONFIGURAZIONE"
.PP
The following configuration variables in
/etc/login\&.defs
change the behavior of this tool:
.PP
\fBENCRYPT_METHOD\fR (string)
.RS 4
This defines the system default encryption algorithm for encrypting passwords (if no algorithm is specified on the command line)\&.
.sp
It can take one of these values:
\fISHA256\fR,
\fISHA512\fR
(default),
\fIYESCRYPT\fR\&. See
crypt(5)
for recommendations\&.
.sp
Note: this only affects the generation of group passwords\&. The generation of user passwords is done by PAM and subject to the PAM configuration\&. It is recommended to set this variable consistently with the PAM configuration\&.
.sp
History: This variable is used by other programs, which may still default to unsafe algorithms such as DES\&. To avoid using unsafe algorithms, the variable should always be specified\&.
.RE
.PP
\fBMAX_MEMBERS_PER_GROUP\fR (number)
.RS 4
Maximum members per group entry\&. When the maximum is reached, a new group entry (line) is started in
/etc/group
(with the same name, same password, and same GID)\&.
.sp
Il valore predefinito \(`e 0, che non pone nessun limite al numero di membri per gruppo\&.
.sp
Questa opzione (dividi gruppo) permette di limitare la lunghezza delle righe nel file \(Fogroup\(Fc\&. Questo \(`e utile per essere certi che le righe per gruppi NIS non eccedano i 1024 caratteri\&.
.sp
Se si deve impostare questo limite, si pu\(`o usare 25\&.
.sp
Nota: la divisione dei gruppi potrebbe non essere supportata da ogni strumento (anche all\*(Aqinterno del pacchetto Shadow)\&. Non si dovrebbe utilizzare questa variabile a meno di esserci forzati\&.
.RE
.PP
\fBSHA_CRYPT_MIN_ROUNDS\fR (number), \fBSHA_CRYPT_MAX_ROUNDS\fR (number)
.RS 4
When
\fBENCRYPT_METHOD\fR
is set to
\fISHA256\fR
or
\fISHA512\fR, this defines the number of SHA rounds used by the encryption algorithm by default (when the number of rounds is not specified on the command line)\&.
.sp
With a lot of rounds, it is more difficult to brute force the password\&. But note also that more CPU resources will be needed to authenticate users\&.
.sp
If not specified, the libc will choose the default number of rounds (5000), which is orders of magnitude too low for modern hardware\&.
.sp
Il valore deve essere compreso tra 1\&.000 e 999\&.999\&.999\&.
.sp
If only one of the
\fBSHA_CRYPT_MIN_ROUNDS\fR
or
\fBSHA_CRYPT_MAX_ROUNDS\fR
values is set, then this value will be used\&.
.sp
If
\fBSHA_CRYPT_MIN_ROUNDS\fR
>
\fBSHA_CRYPT_MAX_ROUNDS\fR, the highest value will be used\&.
.sp
Note: this only affect the generation of group passwords\&. The generation of user passwords is done by PAM and subject to the PAM configuration\&. It is recommended to set this variable consistently with the PAM configuration\&.
.RE
.PP
\fBYESCRYPT_COST_FACTOR\fR (number)
.RS 4
When
\fBENCRYPT_METHOD\fR
is set to
\fIYESCRYPT\fR, this defines the cost factor used by the encryption algorithm by default (when the cost factor is not specified on the command line)\&.
.sp
With a high cost factor, it is more difficult to brute force the password\&. But note also that more CPU resources will be needed to authenticate users\&.
.sp
The value must be inside the 1\-11 range\&.
.sp
Note: this only affect the generation of group passwords\&. The generation of user passwords is done by PAM and subject to the PAM configuration\&. It is recommended to set this variable consistently with the PAM configuration\&.
.RE
.SH "FILE"
.PP
/etc/group
.RS 4
Informazioni sugli account di gruppo\&.
.RE
.PP
/etc/gshadow
.RS 4
Informazioni sicure sugli account di gruppo\&.
.RE
.PP
/etc/login\&.defs
.RS 4
Configurazione del pacchetto password shadow
.RE
.SH "VEDERE ANCHE"
.PP
\fBgpasswd\fR(1),
\fBgroupadd\fR(8),
\fBlogin.defs\fR(5)\&.