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.

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, --badname
	   Allow names that do not conform to standards.

       -c, --comment COMMENT
	   update the comment field of the user in /etc/passwd, which 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. If the current home directory does
	   not exist the new home directory will not be created.

       -e, --expiredate EXPIRE_DATE
	   Specifies 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.

	   An input of -1 or an empty string blanks the account expiration
	   field in the shadow password file. The account will remain
	   available with no expiration date.

	   This option requires the /etc/shadow file. If no entry exists in
	   the /etc/shadow file, the system will automatically create one.

       -f, --inactive INACTIVE
	   Defines the number of days after a password exceeds its maximum age
	   during which the user can still log in by immediately changing
	   their password. 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.

	   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.

	   This option requires the /etc/shadow file. If no entry exist in the
	   /etc/shadow file, the system will automatically create one.

       -g, --gid GROUP
	   The name or numerical ID of the user's new primary 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.

	   The change of the group ownership of files inside of the user's
	   home directory is also not done if the home dir owner uid is
	   different from the current or new user id. This is a safety measure
	   for special home directories such as /.

       -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 must exist.

	   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
	   moves the content of the user's home directory to the new location.
	   If the current home directory does not exist the new home directory
	   will not be created.

	   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
	   allows to change the user ID to a non-unique value.

	   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.

       -p, --password PASSWORD
	   defines a new password for the user. PASSWORD is expected to be
	   encrypted, as returned by crypt (3).

	   Note: Avoid this option on the command line 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, --remove
	   Remove the user from named supplementary group(s). Use only with
	   the -G option.

       -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.

       -P, --prefix PREFIX_DIR
	   Apply changes within the directory tree starting with PREFIX_DIR
	   and use as well the configuration files located there. 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
	   changes the user's login shell. An empty string for SHELL empties
	   the field in /etc/passwd and logs the user into the system's
	   default shell.

       -u, --uid UID
	   The new 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.

	   The change of the user ownership of files inside of the user's home
	   directory is also not done if the home dir owner uid is different
	   from the current or new user id. This is a safety measure for
	   special home directories such as /.

	   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 user's 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 user's 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 user's 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 user's 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
	   defines the SELinux user to be mapped with LOGIN. An empty string
	   ("") will remove the respective entry (if any). Note that the
	   shadow system doesn't store the selinux-user, it uses semanage(8)
	   for that.

       --selinux-range SERANGE
	   defines the SELinux MLS range for the new account. Note that the
	   shadow system doesn't store the selinux-range, it uses semanage(8)
	   for that.

	   This option is only valid if the -Z (or --selinux-user) option is
	   specified.

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 operating systems 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. 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 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 4.18.0		  06/27/2025			    USERMOD(8)