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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.

       By default, a group will also be created for the new user (see -g, -N, -U, and
       USERGROUPS_ENAB).

OPZIONI

       Il comando useradd accetta le seguenti opzioni:

       -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.

           If this option is not specified, useradd will use the base directory specified by the
           HOME variable in /etc/default/useradd, or /home by default.

       -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.

       -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.

       -D, --defaults
           See below, the subsection "Changing the default values".

       -e, --expiredate EXPIRE_DATE
           La data in cui l'account dell'utente verrà disabilitato. La data è specificata nel
           formato MM/GG/AA.

           If not specified, useradd will use the default expiry date specified by the EXPIRE
           variable in /etc/default/useradd, or an empty string (no expiry) by default.

       -f, --inactive INACTIVE
           The number of days after a password expires until the account is permanently disabled.
           A value of 0 disables the account as soon as the password has expired, and a value of
           -1 disables the feature.

           If not specified, useradd will use the default inactivity period specified by the
           INACTIVE variable in /etc/default/useradd, or -1 by default.

       -g, --gid GROUP
           Il nuome o numero del nuovo gruppo di connessione dell'utente. Il nome del gruppo deve
           esistere. Un numero di gruppo deve riferirsi ad un gruppo già esistente.

           If not specified, the behavior of useradd will depend on the USERGROUPS_ENAB variable
           in /etc/login.defs. If this variable is set to yes (or -U/--user-group is specified on
           the command line), a group will be created for the user, with the same name as her
           loginname. If the variable is set to no (or -N/--no-user-group is specified on the
           command line), useradd will set the primary group of the new user to the value
           specified by the GROUP variable in /etc/default/useradd, or 100 by default.

       -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.

       -k, --skel SKEL_DIR
           The skeleton directory, which contains files and directories to be copied in the
           user's home directory, when the home directory is created by useradd.

           This option is only valid if the -m (or --create-home) option is specified.

           If this option is not set, the skeleton directory is defined by the SKEL variable in
           /etc/default/useradd or, by default, /etc/skel.

           If possible, the ACLs and extended attributes are copied.

       -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

       -l, --no-log-init
           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.

           For the compatibility with previous Debian's useradd, the -O option is also supported.

       -m, --create-home
           Create the user's home directory if it does not exist. The files and directories
           contained in the skeleton directory (which can be defined with the -k option) will be
           copied to the home directory.

           By default, if this option is not specified and CREATE_HOME is not enabled, no home
           directories are created.

       -M
           Do no create the user's home directory, even if the system wide setting from
           /etc/login.defs (CREATE_HOME) is set to yes.

       -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 /etc/login.defs.

       -o, --non-unique
           Allow the creation of a user account with a duplicate (non-unique) UID.

           This option is only valid in combination with the -u option.

       -p, --password PASSWORD
           The encrypted password, as returned by crypt(3). The default is to disable the
           password.

           Note: This option is not recommended because the password (or encrypted password) will
           be visible by users listing the processes.

           You should make sure the password respects the system's password policy.

       -r, --system
           Create a system account.

           System users will be created with no aging information in /etc/shadow, and their
           numeric identifiers are chosen in the SYS_UID_MIN-SYS_UID_MAX range, defined in
           /etc/login.defs, instead of UID_MIN-UID_MAX (and their GID counterparts for the
           creation of groups).

           Note that useradd will not create a home directory for such an user, regardless of the
           default setting in /etc/login.defs (CREATE_HOME). You have to specify the -m options
           if you want a home directory for a system account to be created.

       -s, --shell SHELL
           The name of the user's login shell. The default is to leave this field blank, which
           causes the system to select the default login shell specified by the SHELL variable in
           /etc/default/useradd, or an empty string by default.

       -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 /etc/login.defs.

       -Z, --selinux-user SEUSER
           The SELinux user for the user's login. The default is to leave this field blank, which
           causes the system to select the default SELinux user.

   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.

           This option sets the HOME variable in /etc/default/useradd.

       -e, --expiredate EXPIRE_DATE
           La data in cui l'account dell'utente verrà disabilitato.

           This option sets the EXPIRE variable in /etc/default/useradd.

       -f, --inactive INACTIVE
           Il numero di giorni dopo la scadenza di una password prima che l'account venga
           disabilitato.

           This option sets the INACTIVE variable in /etc/default/useradd.

       -g, --gid GROUP
           The group name or ID for a new user's initial group (when the -N/--no-user-group is
           used or when the USERGROUPS_ENAB variable is set to no in /etc/login.defs. The named
           group must exist, and a numerical group ID must have an existing entry.

           This option sets the GROUP variable in /etc/default/useradd.

       -s, --shell SHELL
           The name of a new user's login shell.

           This option sets the SHELL variable in /etc/default/useradd.

NOTE

       The system administrator is responsible for placing the default user files in the
       /etc/skel/ directory (or any other skeleton directory specified in /etc/default/useradd or
       on the command line).

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, followed by lower case letters, digits, underscores, or dashes. They can end
       with 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.). Note that using a slash ('/') may break the default algorithm for the
       definition of the user's home directory.

       Usernames may only be up to 32 characters long.

CONFIGURATION

       The following configuration variables in /etc/login.defs change the behavior of this tool:

       CREATE_HOME (boolean)
           Indicate if a home directory should be created by default for new users.

           This setting does not apply to system users, and can be overridden on the command
           line.

       GID_MAX (number), GID_MIN (number)
           Range of group IDs used for the creation of regular groups by useradd, groupadd, 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 file mode creation mask is initialized to this value. If not specified, the mask
           will be initialized to 022.

           useradd and newusers use this mask to set the mode of the home directory they create

           It is also used by pam_umask as the default umask value.

       USERGROUPS_ENAB (boolean)
           If set to yes, userdel will remove the user's group if it contains no more members,
           and useradd will create by default a group with the name of the user.

FILE

       /etc/passwd
           informazioni sugli account utente.

       /etc/shadow
           Informazioni sicure sugli account di utenti.

       /etc/group
           Informazioni sugli account di gruppo.

       /etc/gshadow
           Informazioni sicure 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).