デフォルトでは CRYPT でパスワードが生成される．
% htpasswd
Usage:
htpasswd [-cmdpsD] passwordfile username
htpasswd -b[cmdpsD] passwordfile username password
htpasswd -n[mdps] username
htpasswd -nb[mdps] username password
-c Create a new file.
-n Don't update file; display results on stdout.
-m Force MD5 encryption of the password.
-d Force CRYPT encryption of the password (default).
-p Do not encrypt the password (plaintext).
-s Force SHA encryption of the password.
-b Use the password from the command line rather
than prompting for it.
-D Delete the specified user.
On Windows, NetWare and TPF systems the '-m' flag is used
by default.
On all other systems, the '-p' flag will probably not work.
