htpasswd is used to create and update the flat-files used to store usernames and password for basic authentication of HTTP users. If htpasswd cannot access a file, such as not being able to write to the output file or not being able to read the file in order to update it, it returns an error status and makes no changes.
Create a new password file

Following command will creates a new file and stores a record in it for user jerry. The user is prompted for the password. If the file exists and cannot be read, or cannot be written, it is not altered and htpasswd will display a message and return an error status.
# htpasswd -c /home/pwww/.htpasswd jerry
Change or update password

To add or modifies the password for user tom, enter:
# htpasswd /home/pwww/.htpasswd-users tom

The user is prompted for the password.