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     PASSWD(1)                                               PASSWD(1)

          passwd - change login password

          passwd [ -an ] [ name ]

          This command changes (or installs) a password associated
          with the user name (your own name by default).

          The program prompts for the old password and then for the
          new one.  The caller must supply both.  The new password
          must be typed twice, to forestall mistakes.

          New passwords must be at least four characters long if they
          use a sufficiently rich alphabet and at least six characters
          long if monocase.  These rules are relaxed if you are insis-
          tent enough.

          Only the owner of the name or the super-user may change a
          password; the owner must prove he knows the old password.

          If the -a option is given, passwd prompts for new values of
          certain fields of the password file entry.

          The super-user may use the -n option to install new users.
          The prompts are self-explanatory, and most of the defaults
          obvious.  A null response to the ``UID:'' prompt assigns a
          numeric userid one greater than the largest one previously
          in /etc/passwd. A null response to the ``Directory:'' prompt
          assigns the user a home directory in /usr. If the first
          character of the response to this prompt is an asterisk, the
          remaining characters are taken as the name of the new user's
          home directory, and a symbolic link to this directory is
          placed in /usr. A user can be assigned a directory with a
          name of the form /dir/username by replying *dir.

          A new user's home directory starts with a file named
          .profile. This file is a copy of /etc/stdprofile with \N
          replaced by the user's name, and \D replaced by the name of
          the user's home directory.


          passwd(5), crypt(3)
          Robert Morris and Ken Thompson, UNIX password security

     PASSWD(1)                                               PASSWD(1)

          The password file information should be kept in a different
          data structure allowing indexed access.