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       -a, --append

           Add the user to the supplementary group(s). Use only with the -G option.

       -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.

       -U, --user-group

           Create a group with the same name as the user, and add the user to this group.

           The default behavior (if the -g, -N, and -U options are not specified) is defined by the USERGROUPS_ENAB variable in /etc/login.defs.

       -s, --shell 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

           specified by the SHELL variable in /etc/default/useradd, or an empty string by default.

       -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.

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SHELL BUILTIN COMMANDS

       set [--abefhkmnptuvxBCEHPT] [-o option-name] [arg ...]

       set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg ...]

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              -e      Exit  immediately if a pipeline (which may consist of a single simple command), a list, or a compound command (see SHELL GRAMMAR above),  exits with a non-zero status.  The shell does not exit if the command that fails is part of the command list immediately following a while  or  until

                      keyword, part of the test following the if or elif reserved words, part of any command executed in a && or || list except the command following

                      the final && or ||, any command in a pipeline but the last, or if the command's return value is being inverted with !.  If a  compound  command

                      other  than  a subshell returns a non-zero status because a command failed while -e was being ignored, the shell does not exit.  A trap on ERR,

                      if set, is executed before the shell exits.  This option applies to the shell environment and each subshell environment separately (see COMMAND

                      EXECUTION ENVIRONMENT above), and may cause subshells to exit before executing all the commands in the subshell.

                      If a compound command or shell function executes in a context where -e is being ignored, none of the commands executed within the compound com‐

                      mand or function body will be affected by the -e setting, even if -e is set and a command returns a failure status.  If a compound  command  or

                      shell  function  sets  -e while executing in a context where -e is ignored, that setting will not have any effect until the compound command or

                      the command containing the function call completes.