Verify user and password against a file created by htpasswd

You can use the htpasswd tool for this.

# create htpasswd_file with user:password
$ htpasswd -cb htpasswd_file user password
Adding password for user user

# verify password for user
$ htpasswd -vb htpasswd_file user wrongpassword
password verification failed

$ htpasswd -vb htpasswd_file user password
Password for user user correct.

Exit status is 0 for success, 3 for failure.