useradd — Create a new user.
useradd creates a new user with specified options like username, home dir, group details, password, etc …
# useradd usr1 — Add new user usr1 with default settings.
# useradd usr1 -d /home2/usr1 — Create the new user’s home dir in /home2
# useradd usr1 -e 2005-04-30 — From 30/4/2005 the user acc will be disabled.
# useradd usr1 -f 6 — After passwd expires, system will allow the user to login for 6 days with a warning to change his passwd.
# useradd usr1 -g staff -G student,lect, prof — Set his initial group as staff and sublimentry group as office, lect, prof.
# useradd usr1 -p $1$d8 — Create the usr1 with the given encrypted password. For No passwd, acc disabled.
# useradd usr1 -s /bin/csh — Set C Shell as the default login shell for the usr1.
Read: man useradd