$ apropos -s1,8 add -a user
addgroup (8)         - add a user or group to the system
adduser (8)          - add a user or group to the system
h5jam (1)            - Add a user block to a HDF5 file
pam_issue (8)        - PAM module to add issue file to user prompt
useradd (8)          - create a new user or update default new user information