USERADD linux command manual

USERADD(8)                                                         USERADD(8)

       useradd - Create a new user or update default new user information

       useradd [-c comment] [-d home_dir]
               [-e expire_date] [-f inactive_time]
               [-g initial_group] [-G group[,...]]
               [-m [-k skeleton_dir] | -M] [-n] [-o] [-p passwd] [-r]
               [-s shell] [-u uid] login

       useradd -D [-g default_group] [-b default_home]
               [-e default_expire_date] [-f default_inactive]
               [-s default_shell]

   Creating New Users
       When  invoked without the -D option, the useradd command creates a new
       user account using the values specified on the command  line  and  the
       default  values from the system.  The new user account will be entered
       into the system files as needed, the home directory will  be  created,
       and  initial files copied, depending on the command line options.  The
       version provided with Red Hat Linux will create a group for each  user
       added to the system, unless the -n option is given.  The options which
       apply to the useradd command are:

       -c comment
              The new user's password file comment field.

       -d 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 default_home and use that as the login directory  name.

       -e expire_date
              The  date on which the user account will be disabled.  The date
              is specified in the format YYYY-MM-DD.

       -f inactive_days
              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.  The default value is -1.

       -g initial_group
              The  group  name  or  number of the user's initial login group.
              The group name must exist.  A group number  must  refer  to  an
              already existing group.  The default group number is 1 or what-
              ever is specified in /etc/default/useradd.

       -G group,[...]
              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.  The
              default is for the user to belong only to the initial group.

       -m     The user's home directory will be created if it does not exist.
              The  files contained in skeleton_dir will be copied to the home
              directory if the -k option is used, otherwise  the  files  con-
              tained in /etc/skel will be used instead.  Any directories con-
              tained in skeleton_dir or /etc/skel  will  be  created  in  the
              user's  home directory as well.  The -k option is only valid in
              conjunction with the -m option.  The default is to  not  create
              the directory and to not copy any files.

       -M     The user home directory will not be created, even if the system
              wide settings from /etc/login.defs is to create home dirs.

       -n     A group having the same name as the user  being  added  to  the
              system  will  be  created by default. This option will turn off
              this Red Hat Linux specific behavior.

       -o     Allow create user with duplicate (non-unique) UID.

       -p passwd
              The encrypted password, as returned by crypt(3).   The  default
              is to disable the account.

       -r     This  flag  is used to create a system account. That is, a user
              with  a  UID  lower  than  the  value  of  UID_MIN  defined  in
              /etc/login.defs  and  whose password does not expire. Note that
              useradd will not create a home  directory  for  such  an  user,
              regardless of the default setting in /etc/login.defs.  You have
              to specify -m option if you want a home directory for a  system
              account to be created.  This is an option added by Red Hat.

       -s shell
              The  name  of  the user's login shell.  The default is to leave
              this field blank, which causes the system to select the default
              login shell.

       -u uid The  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 default is to use the smallest ID value greater
              than 99 and greater than every other user.   Values  between  0
              and 99 are typically reserved for system accounts.

   Changing the default values
       When  invoked with the -D option, useradd will either display the cur-
       rent default values, or update the default  values  from  the  command
       line.  The valid options are

       -b default_home
              The  initial  path prefix for a new user's home directory.  The
              user's name will be affixed to the end of default_home to  cre-
              ate  the  new  directory name if the -d option is not used when
              creating a new account.

       -e default_expire_date
              The date on which the user account is disabled.

       -f default_inactive
              The number of days after a  password  has  expired  before  the
              account will be disabled.

       -g default_group
              The group name or ID for a new user's initial group.  The named
              group must exist, and a numerical group ID must have an  exist-
              ing entry .

       -s default_shell
              The name of the new user's login shell.  The named program will
              be used for all future new user accounts.

       If no options are specified, useradd displays the current default val-

       The  system  administrator is responsible for placing the default user
       files in the /etc/skel directory.
       This version of useradd was modified  by  Red  Hat  to  suit  Red  Hat
       user/group conventions.

       You may not add a user to an NIS group.  This must be performed on the
       NIS server.

       /etc/passwd - user account information
       /etc/shadow - secure user account information
       /etc/group - group information
       /etc/gshadow - secure group information
       /etc/default/useradd - default information
       /etc/login.defs - system-wide settings
       /etc/skel - directory containing default files

       chfn(1),  chsh(1),  passwd(1),  crypt(3),  groupadd(8),   groupdel(8),
       groupmod(8), userdel(8), usermod(8)

       Julianne Frances Haugh (