USERMOD(8)                (02/07/2020)                 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

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              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.

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          -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.

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          -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,

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              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

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              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.

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          /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).

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