NEWUSERS(8) System Management Commands NEWUSERS(8)

newusers - Mettre à jour, ou créer de nouveaux utilisateurs par lots

newusers [options] [file]

The newusers command reads a file (or the standard input by default) and uses this information to update a set of existing users or to create new users. Each line is in the same format as the standard password file (see passwd(5)) with the exceptions explained below:

pw_name:pw_passwd:pw_uid:pw_gid:pw_gecos:pw_dir:pw_shell

pw_name

C'est le nom de l'utilisateur.

It can be the name of a new user or the name of an existing user (or a user created before by newusers). In case of an existing user, the user's information will be changed, otherwise a new user will be created.

pw_passwd

If this field is not empty, it will be encrypted and used as the new value of the encrypted password.

pw_uid

Ce champ est utilisé pour définir l'UID de l'utilisateur.

If the field is empty, a new (unused) UID will be defined automatically by newusers.

Si ce champ contient un nombre, ce nombre sera utilisé comme UID.

If this field contains the name of an existing user (or the name of a user created before by newusers), the UID of the specified user will be used.

Si l'UID d'un utilisateur existant est modifié, vous devrez configurer vous-même le propriétaire des fichiers de l'utilisateur.

pw_gid

Ce champ est utilisé pour définir l'identifiant du groupe primaire de l'utilisateur.

If this field contains the name of an existing group (or a group created before by newusers), the GID of this group will be used as the primary group ID for the user.

Si ce champ est un nombre, ce nombre sera utilisé comme identifiant de groupe primaire de cet utilisateur. Si aucun groupe n'existe avec ce GID, un nouveau groupe sera créé avec ce GID et le nom de l'utilisateur.

If this field is empty, a new group will be created with the name of the user and a GID will be automatically defined by newusers to be used as the primary group ID for the user and as the GID for the new group.

If this field contains the name of a group which does not exist (and was not created before by newusers), a new group will be created with the specified name and a GID will be automatically defined by newusers to be used as the primary group ID for the user and GID for the new group.

pw_gecos

Ce champ est copié dans le champ GECOS de l'utilisateur.

pw_dir

Ce champ est utilisé pour définir le répertoire personnel de l'utilisateur.

If this field does not specify an existing directory, the specified directory is created, with ownership set to the user being created or updated and its primary group. Note that newusers does not create parent directories of the new user's home directory. The newusers command will fail to create the home directory if the parent directories do not exist, and will send a message to stderr informing the user of the failure. The newusers command will not halt or return a failure to the calling shell if it fails to create the home directory, it will continue to process the batch of new users specified.

If the home directory of an existing user is changed, newusers does not move or copy the content of the old directory to the new location. This should be done manually.

pw_shell

Ce champ définit l'interpréteur de commande de l'utilisateur. Aucune vérification n'est effectuée sur ce champ.

newusers first tries to create or change all the specified users, and then write these changes to the user or group databases. If an error occurs (except in the final writes to the databases), no changes are committed to the databases.

Lors du premier passage, les utilisateurs sont créés avec un mot de passe verrouillé (les mots de passe ne sont pas modifiés pour les utilisateurs non créés). Un second passage est utilisé pour mettre à jour les mots de passe en utilisant PAM. Les échecs de mise à jour des mots de passe sont signalés, mais n'empêchent pas les mises à jour des autres mots de passe.

Cette commande a été conçue pour les gros systèmes pour lesquels un grand nombre de comptes sont mis à jour en même temps.

The options which apply to the newusers command are:

--badname 

Allow names that do not conform to standards.

-h, --help

Afficher un message d'aide et quitter.

-r, --system

Créer un compte système.

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 login.defs, instead of UID_MIN-UID_MAX (and their GID counterparts for the creation of groups).

-R, --root CHROOT_DIR

Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory. Only absolute paths are supported. No SELINUX support.

Le fichier d'entrée doit être correctement protégé puisqu'il contient des mots de passe en clair.

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, groupadd, or newusers.

The default value for GID_MIN (resp. GID_MAX) is 1000 (resp. 60000).

HOME_MODE (number)

The mode for new home directories. If not specified, the UMASK is used to create the mode.

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

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).

La valeur par défaut est 0, ce qui signifie qu'il n'y a pas de limites pour le nombre de membres dans un groupe.

Cette fonctionnalité (groupe découpé) permet de limiter la longueur des lignes dans le fichier de groupes. Ceci est utile pour s'assurer que les lignes pour les groupes NIS ne sont pas plus grandes que 1024 caractères.

Si vous avez besoin de configurer cette limite, vous pouvez utiliser 25.

Remarque : les groupes découpés ne sont peut-être pas pris en charge par tous les outils (même dans la suite d'outils Shadow). Vous ne devriez pas utiliser cette variable, sauf si vous en avez vraiment besoin.

PASS_MAX_DAYS (number)

Nombre maximum de jours de validité d'un mot de passe. Après cette durée, une modification du mot de passe est obligatoire. S'il n'est pas précisé, la valeur de -1 est utilisée (ce qui enlève toute 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 value of -1 means no warning is given. If not specified, no warning will be provided.

SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)

If /etc/subuid exists, the commands useradd and newusers (unless the user already have subordinate group IDs) allocate SUB_GID_COUNT unused group IDs from the range SUB_GID_MIN to SUB_GID_MAX for each new user.

The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are respectively 100000, 600100000 and 65536.

SUB_GID_DETERMINISTIC (boolean)

If set to yes, the commands useradd, usermod, and newusers will calculate subordinate GID ranges deterministically based on the user's UID instead of searching for the next free range. The formula used is: 
      start = SUB_GID_MIN + ((UID - UID_MIN) * SUB_GID_COUNT)
      end   = start + SUB_GID_COUNT - 1

This ensures the same UID always receives the same subordinate GID range on every system, making it suitable for environments with centralized user management (LDAP, NIS, etc.) or synchronized UIDs across systems.

If SUB_GID_DETERMINISTIC is enabled, you can use usermod --add-subgids -S to produce deterministic subgids.

WARNING: Because UID_MIN is used to calculate the ranges, any change of UID_MIN will change the ranges calculated. SUB_GID_COUNT is used to calculate the ranges, any change of SUB_GID_COUNT will change the ranges calculated. Users with identities less than UID_MIN are incompatible with SUB_GID_DETERMINISTIC, but can still be set manually.

WARNING: Do not mix deterministic and linear (default) allocation on the same system or across systems sharing /etc/subgid via network storage (NFS, etc.). Mixing allocation methods will cause subordinate ID range conflicts and overlaps .

The default value for SUB_GID_DETERMINISTIC is no.

Range Calculation Examples

With default configuration (UID_MIN=1000, SUB_GID_MIN=100000, SUB_GID_COUNT=65536):

UID Calculation Subordinate GID Range
1000 100000 + ((1000-1000) * 65536) 100000-165535
1001 100000 + ((1001-1000) * 65536) 165536-231071
1002 100000 + ((1002-1000) * 65536) 231072-296607
1100 100000 + ((1100-1000) * 65536) 6653600-6719135

Subordinate ID Space Planning

When planning subordinate ID allocation, calculate the maximum number of users the space can accommodate:

      capacity = (SUB_GID_MAX - SUB_GID_MIN) / SUB_GID_COUNT

With default values: (600100000 - 100000) / 65536 ≈ 9155 users.

For high-density environments with many users and smaller allocations:

        SUB_GID_COUNT  4096
        SUB_GID_MIN    100000
        SUB_GID_MAX    10000000

This gives: (10000000 - 100000) / 4096 ≈ 2417 users.

UNSAFE_SUB_GID_DETERMINISTIC_WRAP (boolean)

WARNING: SECURITY RISK - MAY CAUSE RANGE OVERLAPS AND PRIVILEGE ESCALATION!

Only effective when SUB_GID_DETERMINISTIC is set to yes.

When set to yes (WRAP MODE), allows the deterministic range calculation to wrap around using modulo arithmetic when a UID would overflow the configured subordinate ID space. The subordinate ID space is treated as a ring buffer.

WARNING: Range overlaps can lead to container escapes and privilege escalation. For example, with SUB_GID_MIN=100000, SUB_GID_MAX=200000, SUB_GID_COUNT=65536, User A (UID 1000) gets range [100000, 165535] and User B (UID 1001) wraps and overlaps with User A. User B's container can now access files from User A's containers.

Use only in development, testing, or tightly constrained lab environments.

When set to no (default), any arithmetic overflow or range exceeding SUB_GID_MAX is a hard error. This guarantees non-overlapping, monotonic allocation.

The default value for UNSAFE_SUB_GID_DETERMINISTIC_WRAP is no.

SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)

If /etc/subuid exists, the commands useradd and newusers (unless the user already have subordinate user IDs) allocate SUB_UID_COUNT unused user IDs from the range SUB_UID_MIN to SUB_UID_MAX for each new user.

The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are respectively 100000, 600100000 and 65536.

SUB_UID_DETERMINISTIC (boolean)

If set to yes, the commands useradd, usermod, and newusers will calculate subordinate UID ranges deterministically based on the user's UID instead of searching for the next free range. The formula used is: 
      start = SUB_UID_MIN + ((UID - UID_MIN) * SUB_UID_COUNT)
      end   = start + SUB_UID_COUNT - 1

This ensures the same UID always receives the same subordinate UID range on every system, making it suitable for environments with centralized user management (LDAP, NIS, etc.) or synchronized UIDs across systems.

If SUB_UID_DETERMINISTIC is enabled, you can use usermod --add-subuids -S to produce deterministic subuids.

WARNING: Because UID_MIN is used to calculate the ranges, any change of UID_MIN will change the ranges calculated. SUB_UID_COUNT is used to calculate the ranges, any change of SUB_UID_COUNT will change the ranges calculated. Users with identities less than UID_MIN are incompatible with SUB_UID_DETERMINISTIC, but can still be set manually.

WARNING: Do not mix deterministic and linear (default) allocation on the same system or across systems sharing /etc/subuid via network storage (NFS, etc.). Mixing allocation methods will cause subordinate ID range conflicts and overlaps .

The default value for SUB_UID_DETERMINISTIC is no.

Range Calculation Examples

With default configuration (UID_MIN=1000, SUB_UID_MIN=100000, SUB_UID_COUNT=65536):

UID Calculation Subordinate UID Range
1000 100000 + ((1000-1000) * 65536) 100000-165535
1001 100000 + ((1001-1000) * 65536) 165536-231071
1002 100000 + ((1002-1000) * 65536) 231072-296607
1100 100000 + ((1100-1000) * 65536) 6653600-6719135

Subordinate ID Space Planning

When planning subordinate ID allocation, calculate the maximum number of users the space can accommodate:

      capacity = (SUB_UID_MAX - SUB_UID_MIN) / SUB_UID_COUNT

With default values: (600100000 - 100000) / 65536 ≈ 9155 users.

For high-density environments with many users and smaller allocations:

        SUB_UID_COUNT  4096
        SUB_UID_MIN    100000
        SUB_UID_MAX    10000000

This gives: (10000000 - 100000) / 4096 ≈ 2417 users.

UNSAFE_SUB_UID_DETERMINISTIC_WRAP (boolean)

WARNING: SECURITY RISK - MAY CAUSE RANGE OVERLAPS AND PRIVILEGE ESCALATION!

Only effective when SUB_UID_DETERMINISTIC is set to yes.

When set to yes (WRAP MODE), allows the deterministic range calculation to wrap around using modulo arithmetic when a UID would overflow the configured subordinate ID space. The subordinate ID space is treated as a ring buffer.

WARNING: Range overlaps can lead to container escapes and privilege escalation. For example, with SUB_UID_MIN=100000, SUB_UID_MAX=200000, SUB_UID_COUNT=65536, User A (UID 1000) gets range [100000, 165535] and User B (UID 1001) wraps and overlaps with User A. User B's container can now access files from User A's containers.

Use only in development, testing, or tightly constrained lab environments.

When set to no (default), any arithmetic overflow or range exceeding SUB_UID_MAX is a hard error. This guarantees non-overlapping, monotonic allocation.

The default value for UNSAFE_SUB_UID_DETERMINISTIC_WRAP is no.

SYS_GID_MAX (number), SYS_GID_MIN (number)

Range of group IDs used for the creation of system groups by useradd, groupadd, or newusers.

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)

Range of user IDs used for the creation of system users by useradd or newusers.

The default value for SYS_UID_MIN (resp. SYS_UID_MAX) is 101 (resp. UID_MIN-1).

UID_MAX (number), UID_MIN (number)

Range of user IDs used for the creation of regular users by useradd or newusers.

The default value for UID_MIN (resp. UID_MAX) is 1000 (resp. 60000).

UMASK (number)

Valeur d'initialisation du masque de permissions. S'il n'est pas précisé, le masque des permissions sera initialisé à 022.

useradd and newusers use this mask to set the mode of the home directory they create if HOME_MODE is not set.

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

/etc/passwd

Informations sur les comptes des utilisateurs.

/etc/shadow

Informations sécurisées sur les comptes utilisateurs.

/etc/group

Informations sur les groupes.

/etc/gshadow

Informations sécurisées sur les groupes.

/etc/login.defs

Configuration de la suite des mots de passe cachés « shadow password ».

/etc/pam.d/newusers

PAM configuration for newusers.

/etc/subgid

IDs des groupes subalternes d'un utilisateur.

/etc/subuid

IDs de utilisateurs subalternes d'un utilisateur.

login.defs(5), passwd(1), subgid(5), subuid(5), useradd(8).

30/07/2026 shadow-utils 4.20.0