계정생성 - useradd useradd [-u uid [-o]] [-g group] [-G group[,group]...] [-d dir] [-s shell] [-c comment] [-m [-i] [-k skel_dir]] [-f inactive] [-e expire] [-r update_homedir_ownership] [-p encrypted_password] [-t template] [-P -S alternate_password_file] login useradd -D [-g group] [-b base_dir] [-f inactive] [-e expire] [-r update_homedir_ownership] [-k skel_dir] [-s shell] [-c comment] [-O allow..