[CentOS-devel] Command / utility to encrypt password which can be used for creating user account

Actually it is off topic for this particular mailing list....
Anyway:
1)  your command is ok if you use single quotes when directly putting
the encrypted string instead of double quotes

$ sudo useradd -c "your user" -m your_user -p 'encrypted password'

2) or you could use what sugggested by Banyan using command
substitution ( `...` or the more Posix compliant and readable $(...)
mechanism) that works instead with double quotes

Gianluca