table of contents
USERADD(8) | Comandi per la gestione del si | USERADD(8) |
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¶
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¶
The options which apply to the useradd command are:
-b, --base-dir BASE_DIR
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
-d, --home-dir HOME_DIR
-D, --defaults
-e, --expiredate EXPIRE_DATE
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
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
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]]]
-h, --help
-k, --skel SKEL_DIR
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.
Se possibile vengono copiate le ACL e gli attributi estesi.
-K, --key KEY=VALUE
Example: -K PASS_MAX_DAYS=-1 can be used when creating system account to turn off password aging, 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
By default, the user's entries in the lastlog and faillog databases are reset to avoid reusing the entry from a previously deleted user.
-m, --create-home
By default, if this option is not specified and CREATE_HOME is not enabled, no home directories are created.
The directory where the user's home directory is created must exist and have proper SELinux context and permissions. Otherwise the user's home directory cannot be created or accessed.
-M, --no-create-home
-N, --no-user-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.
-o, --non-unique
This option is only valid in combination with the -u option.
-p, --password PASSWORD
Note: This option is not recommended because the password (or encrypted password) will be visible by users listing the processes.
Ci si deve accertare che la password rispetti le norme delle password del sistema.
-r, --system
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 a 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.
-R, --root CHROOT_DIR
-P, --prefix PREFIX_DIR
-s, --shell SHELL
-u, --uid UID
See also the -r option and the UID_MAX description.
-U, --user-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
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
This option sets the HOME variable in /etc/default/useradd.
-e, --expiredate EXPIRE_DATE
This option sets the EXPIRE variable in /etc/default/useradd.
-f, --inactive INACTIVE
This option sets the INACTIVE variable in /etc/default/useradd.
-g, --gid GROUP
This option sets the GROUP variable in /etc/default/useradd.
-s, --shell 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¶
Non è possibile aggiungere un utente ad un gruppo NIS o LDAP. Questo deve essere fatto sul server corrispondente.
Similarly, if the username already exists in an external user database such as NIS or LDAP, useradd will deny the user account creation request.
Usernames may contain only lower and upper case letters, digits, underscores, or dashes. They can end with a dollar sign. Dashes are not allowed at the beginning of the username. Fully numeric usernames and usernames . or .. are also disallowed. It is not recommended to use usernames beginning with . character as their home directories will be hidden in the ls output. In regular expression terms: [a-zA-Z0-9_.][a-zA-Z0-9_.-]*[$]?
I nomi utente non possono eccedere i 32 caratteri di lunghezza.
CONFIGURAZIONE¶
The following configuration variables in /etc/login.defs change the behavior of this tool:
CREATE_HOME (boolean)
Questa impostazione non viene applicata agli utenti di sistema e può essere modificata sulla riga di comando.
GID_MAX (number), GID_MIN (number)
The default value for GID_MIN (resp. GID_MAX) is 1000 (resp. 60000).
MAIL_DIR (string)
MAIL_FILE (string)
The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and userdel to create, move, or delete the user's mail spool.
If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL environment variable.
MAX_MEMBERS_PER_GROUP (number)
Il valore predefinito è 0, che non pone nessun limite al numero di membri per gruppo.
Questa opzione (dividi gruppo) permette di limitare la lunghezza delle righe nel file «group». Questo è utile per essere certi che le righe per gruppi NIS non eccedano i 1024 caratteri.
Se si deve impostare questo limite, si può usare 25.
Nota: la divisione dei gruppi potrebbe non essere supportata da ogni strumento (anche all'interno del pacchetto Shadow). Non si dovrebbe utilizzare questa variabile a meno di esserci forzati.
PASS_MAX_DAYS (number)
PASS_MIN_DAYS (number)
PASS_WARN_AGE (number)
SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are respectively 100000, 600100000 and 65536.
SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are respectively 100000, 600100000 and 65536.
SYS_GID_MAX (number), SYS_GID_MIN (number)
The default value for SYS_GID_MIN (resp. SYS_GID_MAX) is 101 (resp. GID_MIN-1).
SYS_UID_MAX (number), SYS_UID_MIN (number)
The default value for SYS_UID_MIN (resp. SYS_UID_MAX) is 101 (resp. UID_MIN-1).
UID_MAX (number), UID_MIN (number)
The default value for UID_MIN (resp. UID_MAX) is 1000 (resp. 60000).
UMASK (number)
useradd and newusers use this mask to set the mode of the home directory they create
It is also used by login to define users' initial umask. Note that this mask can be overridden by the user's GECOS line (if QUOTAS_ENAB is set) or by the specification of a limit with the K identifier in limits(5).
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
/etc/shadow
/etc/group
/etc/gshadow
/etc/default/useradd
/etc/skel/
/etc/subgid
/etc/subuid
/etc/login.defs
VALORI RESTITUITI¶
The useradd command exits with the following values:
0
1
2
3
4
6
9
10
12
14
VEDERE ANCHE¶
chfn(1), chsh(1), passwd(1), crypt(3), groupadd(8), groupdel(8), groupmod(8), login.defs(5), newusers(8), subgid(5), subuid(5),userdel(8), usermod(8).
07/08/2019 | shadow-utils 4.6 |