Provided by:
passwd_4.1.1-1ubuntu1_i386 
NOME
useradd - crea un nuovo utente o aggiorna le informazioni predefinite
per i nuovi utenti
SINOSSI
useradd [opzioni] LOGIN
useradd -D
useradd -D [opzioni]
DESCRIZIONE
useradd is a low level utility for adding users. On Debian,
administrators should usually use adduser(8) instead.
When invoked without the -D option, the useradd command creates a new
user account using the values specified on the command line plus the
default values from the system. Depending on command line options, the
useradd command will update system files and may also create the new
user´s home directory and copy initial files.
OPZIONI
Il comando useradd accetta le seguenti opzioni:
-c, --comment COMMENT
Any text string. It is generally a short description of the login,
and is currently used as the field for the user´s full name.
-b, --base-dir BASE_DIR
The default base directory for the system if -d HOME_DIR is not
specified. BASE_DIR is concatenated with the account name to
define the home directory. If the -m option is not used, BASE_DIR
must exist.
-D, --defaults
See below, the subsection "Changing the default values".
-d, --home HOME_DIR
The new user will be created using HOME_DIR as the value for the
user´s login directory. The default is to append the LOGIN name to
BASE_DIR and use that as the login directory name. The directory
HOME_DIR does not have to exist but will not be created if it is
missing.
-e, --expiredate EXPIRE_DATE
La data in cui l´account dell´utente verrà disabilitato. La data è
specificata nel formato MM/GG/AA.
-f, --inactive INACTIVE
Il numero di giorni dopo la scadenza della password prima che
l´account verrà permanentemente disabilitato. Un valore pari a 0
disabilita l´account non appena la password è scaduta, ed un valore
pari a -1 disabilita questa caratteristica. Il valore predefinito è
-1.
-g, --gid GROUP
The group name or number of the user´s initial login group. The
group name must exist. A group number must refer to an already
existing group. The default group number is 1 or whatever is
specified in /etc/default/useradd.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
Una lista di gruppi supplementari di cui l´utente è altresì membro.
Ciascun gruppo è separato dal successivo da una virgola, senza
spazi bianchi intermedi. I gruppi sono soggetti alle stesse
restrizioni del gruppo dato con l´opzione -g. Il comportamento
predefinito è che l´utente appartenga solo al gruppo iniziale.
-h, --help
Mostra un messaggio di aiuto ed esce.
-m, --create-home
The user´s home directory will be created if it does not exist. The
files contained in SKEL_DIR will be copied to the home directory if
the -k option is used, otherwise the files contained in /etc/skel
will be used instead. Any directories contained in SKEL_DIR or
/etc/skel will be created in the user´s home directory as well. The
-k option is only valid in conjunction with the -m option. The
default is to not create the directory and to not copy any files.
This option may not function correctly if the username has a / in
it.
-K, --key KEY=VALUE
Overrides /etc/login.defs defaults (UID_MIN, UID_MAX, UMASK,
PASS_MAX_DAYS and others).
Example: -K PASS_MAX_DAYS=-1 can be used when creating system
account to turn off password ageing, even though system account has
no password at all. Multiple -K options can be specified, e.g.: -K
UID_MIN=100
-K UID_MAX=499
Note: -K UID_MIN=10,UID_MAX=499 doesn´t work yet.
For the compatibility with previous Debian´s useradd, the -O option
is also supported.
-l
Do not add the user to the lastlog and faillog databases.
By default, the user´s entries in the lastlog and faillog databases
are resetted to avoid reusing the entry from a previously deleted
user.
-N, --no-user-group
Do not create a group with the same name as the user, but add the
user to the group specified by the -g option or by the GROUP
variable in /etc/default/useradd.
The default behavior (if the -g, -N, and -U options are not
specified) is defined by the USERGROUPS_ENAB variable in
login.defs.
-o, --non-unique
Allow the creation of a user account with a duplicate (non-unique)
UID.
-p, --password PASSWORD
The encrypted password, as returned by crypt(3). The default is to
disable the account.
-s, --shell SHELL
Il nome della shell di login dell´utente. Il comportamento
predefinito è di lasciare vuoto questo campo, che fa sì che il
sistema selezioni la shell di connessione predefinita.
-u, --uid UID
Il valore numerico dell´identificatore (ID) del gruppo. Questo
valore deve essere univoco, a meno che non venga usata l´opzione
-o. Il valore deve essere non-negativo. La scelta predefinita è
quella di usare il minimo valore di ID superiore a 999 e superiore
a qualunque altro gruppo. Valori tra 0 e 999 sono tipicamente
riservati per account di sistema.
-U, --user-group
Create a group with the same name as the user, and add the user to
this group.
The default behavior (if the -g, -N, and -U options are not
specified) is defined by the USERGROUPS_ENAB variable in
login.defs.
Cambiare i valori predefiniti
When invoked with only the -D option, useradd will display the current
default values. When invoked with -D plus other options, useradd will
update the default values for the specified options. Valid
default-changing options are:
-b, --base-dir BASE_DIR
The path prefix for a new user´s home directory. The user´s name
will be affixed to the end of BASE_DIR to form the new user´s home
directory name, if the -d option is not used when creating a new
account.
-e, --expiredate EXPIRE_DATE
La data in cui l´account dell´utente verrà disabilitato.
-f, --inactive INACTIVE
Il numero di giorni dopo la scadenza di una password prima che
l´account venga disabilitato.
-g, --gid GROUP
Il nome o ID del gruppo iniziale per un nuovo utente. Il gruppo
nominato deve esistere, ed un ID numerico di gruppo deve avere una
voce esistente.
-s, --shell SHELL
The name of a new user´s login shell.
NOTE
L´amministratore di sistema è responsabile del posizionamento dei file
predefiniti degli utenti nella directory /etc/skel/.
AVVISI/CAVEAT
You may not add a user to a NIS or LDAP group. This must be performed
on the corresponding server.
Similarly, if the username already exists in an external user database
such as NIS or LDAP, useradd will deny the user account creation
request.
It is usually recommended to only use usernames that begin with a lower
case letter or an underscore, and are only followed by lower case
letters, digits, underscores, dashes, and optionally terminated by a
dollar sign. In regular expression terms: [a-z_][a-z0-9_-]*[$]? On
Debian, the only constraints are that usernames must neither start with
a dash (´-´) nor contain a colon (´:´) or a whitespace (space:´ ´, end
of line: ´\n´, tabulation: ´\t´, etc.).
CONFIGURATION
The following configuration variables in /etc/login.defs change the
behavior of this tool:
GID_MAX (number), GID_MIN (number)
Range of group IDs used for the creation of regular groups by
useradd, useradd, or newusers.
MAIL_DIR (string)
The mail spool directory. This is needed to manipulate the mailbox
when its corresponding user account is modified or deleted. If not
specified, a compile-time default is used.
MAIL_FILE (string)
Defines the location of the users mail spool files relatively to
their home directory.
The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
userdel to create, move, or delete the user´s mail spool.
MAX_MEMBERS_PER_GROUP (number)
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).
The default value is 0, meaning that there are no limits in the
number of members in a group.
This feature (split group) permits to limit the length of lines in
the group file. This is useful to make sure that lines for NIS
groups are not larger than 1024 characters.
If you need to enforce such limit, you can use 25.
Note: split groups may not be supported by all tools (even in the
Shadow toolsuite. You should not use this variable unless you
really need it.
PASS_MAX_DAYS (number)
The maximum number of days a password may be used. If the password
is older than this, a password change will be forced. If not
specified, -1 will be assumed (which disables the restriction).
PASS_MIN_DAYS (number)
The minimum number of days allowed between password changes. Any
password changes attempted sooner than this will be rejected. If
not specified, -1 will be assumed (which disables the restriction).
PASS_WARN_AGE (number)
The number of days warning given before a password expires. A zero
means warning is given only upon the day of expiration, a negative
value means no warning is given. If not specified, no warning will
be provided.
SYS_GID_MAX (number), SYS_GID_MIN (number)
Range of group IDs used for the creation of system groups by
useradd, groupadd, or newusers.
SYS_UID_MAX (number), SYS_UID_MIN (number)
Range of user IDs used for the creation of system users by useradd
or newusers.
UID_MAX (number), UID_MIN (number)
Range of user IDs used for the creation of regular users by useradd
or newusers.
UMASK (number)
The permission mask is initialized to this value. If not specified,
the permission mask will be initialized to 022.
USERGROUPS_ENAB (boolean)
FILE
/etc/passwd
informazioni sugli account utente.
/etc/shadow
Informazioni sicure sugli account di utenti.
/etc/group
Informazioni sugli account di gruppo.
/etc/default/useradd
Default values for account creation.
/etc/skel/
Directory contenente i file predefiniti.
/etc/login.defs
Shadow password suite configuration.
VALORI RESTITUITI
The useradd command exits with the following values:
0
successo
1
can´t update password file
2
sintassi del comando errata
3
invalid argument to option
4
UID already in use (and no -o)
6
il gruppo specificato non esiste
9
username already in use
10
non è possibile aggiornare il file group
12
can´t create home directory
13
can´t create mail spool
VEDERE ANCHE
chfn(1), chsh(1), passwd(1), crypt(3), groupadd(8), groupdel(8),
groupmod(8), login.defs(5), newusers(8), userdel(8), usermod(8).