Ask here, read here.......
Could be your pathing....
$ locate useradd
/usr/bin/seuseradd
/usr/sbin/luseradd
/usr/sbin/useradd
$ /usr/bin/useradd
Code:
usage: useradd [-u uid [-o]] [-g group] [-G group,...]
[-d home] [-s shell] [-c comment] [-m [-k template]]
[-f inactive] [-e expire ] [-p passwd] [-M] [-n] [-r] [-l] name
useradd -D [-g group] [-b base] [-s shell]
[-f inactive] [-e expire ]