The passwd data structure is used to hold information about
entries in the system user data base.  It has at least the following members:
char *pw_name
- The user's login name.
  char *pw_passwd.
- The encrypted password string.
  uid_t pw_uid
- The user ID number.
  gid_t pw_gid
- The user's default group ID number.
  char *pw_gecos
- A string typically containing the user's real name, and possibly other
information such as a phone number.
  char *pw_dir
- The user's home directory, or initial working directory.  This might be
a null pointer, in which case the interpretation is system-dependent.
  char *pw_shell
- The user's default shell, or the initial program run when the user logs in. 
This might be a null pointer, indicating that the system default should
be used. 
  
 |