USERADD(8)

📦
version 4.19.0 · 13 versions
, in fedora 44

👑 USERADD(8) — System Management Commands 👑

okay bestie, welcome to useradd from the System Management Commands section of the manual (section 8, we love a system-admin moment). this is the girlboss that makes new user accounts. she's iconic, she's powerful, and she will absolutely write to your system files, so let's pay attention 💅

✨ NAME ✨

useradd — create a new user or update default new user information 🫶

🌸 SYNOPSIS 🌸

useradd [options] LOGIN

useradd -D

useradd -D [options]

💖 DESCRIPTION 💖

so here's the vibe. when you run useradd without the -D option, she creates a brand new user account, using the values you gave her on the command line plus the default values from your system. bestie is nothing if not thorough ✨

depending on which command line options you pass, useradd will update system files, and she may also create the new user's home directory and copy initial files into it. very "moving you into your new apartment" of her 🏠

by default, a group will also be created for the new user — peep -g, -N, -U, and USERGROUPS_ENAB if you wanna know the tea ☕

🌈 OPTIONS 🌈

the options that apply to the useradd command are, in order, because we are organized queens:

  • --badname — allow names that do not conform to standards. yes she's letting you be chaotic, no we don't recommend it 🙈
  • -b, --base-dir BASE_DIR — this is the default base directory for the system, used when -d HOME_DIR isn't specified. BASE_DIR gets concatenated with the account name to define the home directory. if you don't specify this option, useradd uses the base directory specified by the HOME variable in /etc/default/useradd, or /home by default.
  • --btrfs-subvolume-home — create the user's home directory as a Btrfs subvolume 🦋

if this option isn't specified, useradd follows the default behavior defined by the BTRFS_SUBVOLUME_HOME variable in /etc/default/useradd. if that variable isn't set, the default value is no.

when the --btrfs-subvolume-home command-line option is specified, a Btrfs subvolume is created regardless of any configuration file settings. periodt.

if the parent directory of the user's home directory is not on a Btrfs filesystem, useradd will not create a subvolume. instead she creates a regular directory, prints a warning to standard error, and logs the event via syslog at level LOG_WARN. the user account is still created successfully — no drama, just a heads up 💅

if the filesystem type cannot be determined (e.g., because of insufficient permissions, an I/O error, or a statfs(2) failure), useradd treats this as a fatal error: the home directory is not created, the command exits with a non-zero status (E_HOMEDIR, 12), and an error message is printed. 😭

  • -c, --comment COMMENT — any text string. it's generally a short description of the account, and it's currently used as the field for the user's full name.
  • -d, --home-dir 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 is not created by default. however, it will be created for non-system users if either the -m flag is specified or CREATE_HOME in login.defs is set to true. however, it will never be created if the -M flag is specified.
  • -D, --defaults — see below, the subsection "Changing the default values". 👀
  • -e, --expiredate EXPIRE_DATE — sets the date on which the user account will be disabled. the value can be specified as a date in the YYYY-MM-DD format or as a number of days since 1970-01-01. the date is interpreted using the UTC timezone.

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

  • -f, --inactive INACTIVE — defines the number of days after a password exceeds its maximum age before the user account gets locked. if the user does not change their password within this period of time, their account becomes inactive. this value is stored in the shadow password file. for more information, see shadow(5).

a value of 0 disables the account when the password expires, with no delay. ⏰

a value of -1 empties the respective field in the shadow password file, which means that the inactivity period is not enforced.

if not specified, useradd uses the default inactivity period specified by the INACTIVE variable in /etc/default/useradd, or -1 by default if no value is specified.

  • -F, --add-subids-for-system — update /etc/subuid and /etc/subgid even when creating a system account with the -r option.
  • -g, --gid GROUP — the name or the number of the user's primary group. the group name must exist. a group number must refer to an already existing group. no making up groups, bestie, that's not the vibe 🚫

if not specified, the behavior of useradd depends 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 the 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 1000 by default.

  • -G, --groups GROUP1[,GROUP2,...[,GROUPN]]] — a list of supplementary groups which the user is also a member of. each group is separated from the next by a comma, with no intervening whitespace (so no spaces, she's picky like that). the groups are subject to the same restrictions as the group given with the -g option. the default is for the user to belong only to the initial group. in addition to passing in the -G flag, you can add the option GROUPS to the file /etc/default/useradd which in turn will add all users to those supplementary groups. slay, group membership for everyone 🫶
  • -h, --help — display help message and exit. the "hey bestie what do I do" flag 💖
  • -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.

absolute symlinks that link back to the skel directory will have the /etc/skel prefix replaced with the user's home directory.

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 an account to turn off password aging. 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 reset to avoid reusing the entry from a previously deleted user.

if this option is not specified, useradd will also consult the variable LOG_INIT in the /etc/default/useradd — if set to no the user will not be added to the lastlog and faillog databases.

  • -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.

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. no key, no entry, iykyk 🔑

  • -M, --no-create-home — do not 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 — allows the creation of an account with an already existing UID. 😳

this option is only valid in combination with the -u option. as a user identity serves as key to map between users on one hand and permissions, file ownerships and other aspects that determine the system's behavior on the other hand, more than one login name will access the account of the given UID. so like, multiple names, one identity. chaotic but legal (here).

  • -p, --password PASSWORD — defines an initial password for the account. PASSWORD is expected to be encrypted, as returned by crypt (3). within a shell script, this option allows to create efficiently batches of users.

without this option, the new account will be locked and with no password defined, i.e. a single exclamation mark in the respective field of /etc/shadow. this is a state where the user won't be able to access the account or to define a password himself.

⚠️ Note: avoid this option on the command line because the password (or encrypted password) will be visible by users listing the processes. everybody can see it bestie, it's giving public 💀

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 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.

note that this option will not update /etc/subuid and /etc/subgid. you have to specify the -F options if you want to update the files for a system account to be created.

  • -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.
  • -P, --prefix PREFIX_DIR — apply changes to configuration files under the root filesystem found under the directory PREFIX_DIR. this option does not chroot and is intended for preparing a cross-compilation target. some limitations: NIS and LDAP users/groups are not verified. PAM authentication is using the host files. no SELINUX support.
  • -s, --shell SHELL — sets the path to the user's login shell. without this option, the system will use the SHELL variable specified in /etc/default/useradd, or, if that is as well not set, the field for the login shell in /etc/passwd remains empty. 🐚
  • -u, --uid UID — okay so this is the actual number of the user's ID 💫. It's gotta be unique, unless you're passing -o, and it has to be non-negative — no negative vibes allowed fr. If you don't say anything, useradd just grabs the smallest value that's ≥ UID_MIN and bigger than every other user. Slay, it picks for you.

Also go peek at the -r option and the UID_MAX description, they're part of this story 🫶.

  • -U, --user-group — makes a group with the same name as the user and drops the user right into it. Iconic, honestly.

The default behavior (when you don't specify -g, -N, or -U) is decided by the USERGROUPS_ENAB variable in /etc/login.defs. So it's giving "it depends on your config" energy 💅.

  • -Z, --selinux-user SEUSER — sets the SELinux user for the brand-new account. Skip this option and SELinux just uses its default user. Heads up bestie: the shadow system doesn't store the selinux-user — it uses semanage(8) for that. Periodt.
  • --selinux-range SERANGE — sets the SELinux MLS range for the new account. No option? SELinux uses the default range. And same tea as above: the shadow system doesn't store the selinux-range, semanage(8) handles it.
🚨 This one is only valid if the -Z (or --selinux-user) option is specified. No -Z, no --selinux-range. That's the rule.

✨ Changing the default values ✨

Here's the vibe check: run useradd with only the -D option and it just shows you the current default values 👀. Run -D plus other options and it updates the defaults for whatever options you named.

The valid default-changing options are, and yes there are exactly these:

  • -b, --base-dir BASE_DIR — sets the path prefix for a new user's home directory. The user's name gets affixed to the end of BASE_DIR to form the new home directory name — that is, if you're not using the -d option when creating a new account.

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

  • -e, --expiredate EXPIRE_DATE — sets the date on which newly created user accounts get disabled. Yep, a whole expiration date.

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

  • -f, --inactive INACTIVE — the number of days after a password expires during which the user can still log in. Once that period is up, the account gets locked. Sorry babe.

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

  • -g, --gid GROUP — sets the default primary group for newly created users. It takes group names or a numerical group ID. The named group has to exist, and the GID must have an existing entry — no ghost groups bestie.

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

  • -s, --shell SHELL — defines the default login shell for new users.

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

📝 NOTES 📝

The system administrator is the one responsible for placing the default user files in the /etc/skel/ directory — or any other skeleton directory that's specified in /etc/default/useradd or right on the command line. So if the vibes in new home dirs are off, that's a skel thing 🌸.

💀 CAVEATS 💀

  • You may not add a user to a NIS or LDAP group. That has to be performed on the corresponding server. Not here, not today.
  • Same energy: if the username already exists in an external user database like NIS or LDAP, useradd will deny the user account creation request. It said no 💅.
  • 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 the usernames . or .., are also disallowed.
  • It is not recommended to use usernames beginning with the . character, because their home directories will be hidden in the ls output 🙈. Sneaky, but not in a cute way.
  • Usernames may only be up to 256 characters long. That's the limit, bestie.

🔧 CONFIGURATION 🔧

These are the config variables in /etc/login.defs that change how this tool behaves. Big main-character energy for a config file, I know.

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 it 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.

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

HOME_MODE (number)

The mode for new home directories. If it's 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.

LASTLOG_UID_MAX (number)

Highest user ID number for which lastlog entries should be updated. Since higher user IDs are usually tracked by remote user identity and authentication services, there's no need to create a huge sparse lastlog file for them. Efficient queen 💅.

No LASTLOG_UID_MAX option present in the configuration means there is no user ID limit for writing lastlog entries.

MAIL_DIR (string)

The mail spool directory. This is needed to manipulate the mailbox when its corresponding user account is modified or deleted. If it's not specified, a compile-time default is used. The parameter CREATE_MAIL_SPOOL in /etc/default/useradd determines whether the mail spool should be created.

MAIL_FILE (string)

Defines the location of the user's 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 max 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 there are no limits on the number of members in a group.

This feature (split group) permits limiting the length of lines in the group file. That's useful to make sure lines for NIS groups aren't larger than 1024 characters.

If you need to enforce such a 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, 0 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 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 has 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_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)

If /etc/subuid exists, the commands useradd and newusers (unless the user already has 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.

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)

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 — but only if HOME_MODE is not set.

It's 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. Teamwork fr fr 🫶.

🗂️ FILES 🗂️

  • /etc/passwd — user account information.
  • /etc/shadow — secure user account information.
  • /etc/group — group account information.
  • /etc/gshadow — secure group account information.
  • /etc/default/useradd — default values for account creation.
  • /etc/shadow-maint/useradd-pre.d/*, /etc/shadow-maint/useradd-post.d/* — run-part files to execute during user addition. The environment variable ACTION will be populated with useradd and SUBJECT with the username. useradd-pre.d will be executed prior to any user addition. useradd-post.d will execute after user addition. If a script exits non-zero then execution will terminate 🛑.
  • /etc/skel/ — directory containing default files.
  • /etc/subgid — per user subordinate group IDs.
  • /etc/subuid — per user subordinate user IDs.
  • /etc/login.defs — shadow password suite configuration.

🚪 EXIT VALUES 🚪

The useradd command exits with the following values:

  • 0 — success ✨
  • 1 — can't update password file
  • 2 — invalid command syntax
  • 3 — invalid argument to option
  • 4 — UID already in use (and no -o)
  • 6 — specified group doesn't exist
  • 9 — username or group name already in use
  • 10 — can't update group file
  • 12 — can't create home directory
  • 14 — can't update SELinux user mapping
  • 19 — invalid user or group name

👀 SEE ALSO 👀

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).

and that's the whole page bestie 💖 this one's from shadow-utils 4.19.0, dated 04/29/2026, and it's the USERADD(8) manual — go make some users, you got this 👑🎀

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