USERMOD(8) System Management Commands USERMOD(8)
NAME
usermod - modify a user account
SYNOPSIS
usermod [options] LOGIN
DESCRIPTION
The usermod command modifies the system account files to reflect the
changes that are specified on the command line.
OPTIONS
The options which apply to the usermod command are:
-a, --append
Add the user to the supplementary group(s). Use only with the -G
option.
-b, --badnames
Allow names that do not conform to standards.
-c, --comment COMMENT
The new value of the user's password file comment field. It is
normally modified using the chfn(1) utility.
-d, --home HOME_DIR
The user's new login directory.
If the -m option is given, the contents of the current home
directory will be moved to the new home directory, which is created
if it does not already exist.
-e, --expiredate EXPIRE_DATE
The date on which the user account will be disabled. The date is
specified in the format YYYY-MM-DD.
An empty EXPIRE_DATE argument will disable the expiration of the
account.
This option requires a /etc/shadow file. A /etc/shadow entry will
be created if there were none.
-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.
This option requires a /etc/shadow file. A /etc/shadow entry will
be created if there were none.
-g, --gid GROUP
The group name or number of the user's new initial login group. The
group must exist.
Any file from the user's home directory owned by the previous
primary group of the user will be owned by this new group.
The group ownership of files outside of the user's home directory
must be fixed manually.
-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. The groups are subject to the same
restrictions as the group given with the -g option.
If the user is currently a member of a group which is not listed,
the user will be removed from the group. This behaviour can be
changed via the -a option, which appends the user to the current
supplementary group list.
-l, --login NEW_LOGIN
The name of the user will be changed from LOGIN to NEW_LOGIN.
Nothing else is changed. In particular, the user's home directory
or mail spool should probably be renamed manually to reflect the
new login name.
-L, --lock
Lock a user's password. This puts a '!' in front of the encrypted
password, effectively disabling the password. You can't use this
option with -p or -U.
Note: if you wish to lock the account (not only access with a
password), you should also set the EXPIRE_DATE to 1.
-m, --move-home
Move the content of the user's home directory to the new location.
This option is only valid in combination with the -d (or --home)
option.
usermod will try to adapt the ownership of the files and to copy
the modes, ACL and extended attributes, but manual changes might be
needed afterwards.
-o, --non-unique
When used with the -u option, this option allows to change the user
ID to a non-unique value.
-p, --password PASSWORD
The encrypted password, as returned by crypt(3).
Note: This option is not recommended because the password (or
encrypted password) will be visible by users listing the processes.
The password will be written in the local /etc/passwd or
/etc/shadow file. This might differ from the password database
configured in your PAM configuration.
You should make sure the password respects the system's password
policy.
-R, --root CHROOT_DIR
Apply changes in the CHROOT_DIR directory and use the configuration
files from the CHROOT_DIR directory.
-P, --prefix PREFIX_DIR
Apply changes in the PREFIX_DIR directory and use the configuration
files from the PREFIX_DIR directory. 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
The name of the user's new login shell. Setting this field to blank
causes the system to select the default login shell.
-u, --uid UID
The new numerical value of the user's ID.
This value must be unique, unless the -o option is used. The value
must be non-negative.
The user's mailbox, and any files which the user owns and which are
located in the user's home directory will have the file user ID
changed automatically.
The ownership of files outside of the user's home directory must be
fixed manually.
No checks will be performed with regard to the UID_MIN, UID_MAX,
SYS_UID_MIN, or SYS_UID_MAX from /etc/login.defs.
-U, --unlock
Unlock a user's password. This removes the '!' in front of the
encrypted password. You can't use this option with -p or -L.
Note: if you wish to unlock the account (not only access with a
password), you should also set the EXPIRE_DATE (for example to
99999, or to the EXPIRE value from /etc/default/useradd).
-v, --add-subuids FIRST-LAST
Add a range of subordinate uids to the user's account.
This option may be specified multiple times to add multiple ranges
to a users account.
No checks will be performed with regard to SUB_UID_MIN,
SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.
-V, --del-subuids FIRST-LAST
Remove a range of subordinate uids from the user's account.
This option may be specified multiple times to remove multiple
ranges to a users account. When both --del-subuids and
--add-subuids are specified, the removal of all subordinate uid
ranges happens before any subordinate uid range is added.
No checks will be performed with regard to SUB_UID_MIN,
SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.
-w, --add-subgids FIRST-LAST
Add a range of subordinate gids to the user's account.
This option may be specified multiple times to add multiple ranges
to a users account.
No checks will be performed with regard to SUB_GID_MIN,
SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.
-W, --del-subgids FIRST-LAST
Remove a range of subordinate gids from the user's account.
This option may be specified multiple times to remove multiple
ranges to a users account. When both --del-subgids and
--add-subgids are specified, the removal of all subordinate gid
ranges happens before any subordinate gid range is added.
No checks will be performed with regard to SUB_GID_MIN,
SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.
-Z, --selinux-user SEUSER
The new SELinux user for the user's login.
A blank SEUSER will remove the SELinux user mapping for user LOGIN
(if any).
CAVEATS
You must make certain that the named user is not executing any
processes when this command is being executed if the user's numerical
user ID, the user's name, or the user's home directory is being
changed. usermod checks this on Linux. On other platforms it only uses
utmp to check if the user is logged in.
You must change the owner of any crontab files or at jobs manually.
You must make any changes involving NIS on the NIS server.
CONFIGURATION
The following configuration variables in /etc/login.defs change the
behavior of this tool:
LASTLOG_UID_MAX (number)
Highest user ID number for which the lastlog entries should be
updated. As higher user IDs are usually tracked by remote user
identity and authentication services there is no need to create a
huge sparse lastlog file for them.
No LASTLOG_UID_MAX option present in the configuration means that
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 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.
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_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.
FILES
/etc/group
Group account information.
/etc/gshadow
Secure group account information.
/etc/login.defs
Shadow password suite configuration.
/etc/passwd
User account information.
/etc/shadow
Secure user account information.
/etc/subgid
Per user subordinate group IDs.
/etc/subuid
Per user subordinate user IDs.
SEE ALSO
chfn(1), chsh(1), passwd(1), crypt(3), gpasswd(8), groupadd(8),
groupdel(8), groupmod(8), login.defs(5), subgid(5), subuid(5),
useradd(8), userdel(8).
shadow-utils 4.8.1 02/07/2020 USERMOD(8)