mosquitto_passwd is a tool for managing password files for mosquitto.

Usage: mosquitto_passwd [-H argon2id | -H sha512-pbkdf2] [-c | -D] passwordfile username
       mosquitto_passwd [-H argon2id | -H sha512-pbkdf2] [-c] -b passwordfile username password
       mosquitto_passwd -U passwordfile
 -b : run in batch mode to allow passing passwords on the command line.
 -c : create a new password file. This will overwrite existing files.
 -D : delete the username rather than adding/updating its password.
 -H : specify the hashing algorithm. Defaults to argon2id, which is recommended.
      Mosquitto 2.0 and earlier defaulted to sha512-pbkdf2.
      Mosquitto 1.6 and earlier defaulted to sha512.
 -U : update a plain text password file to use hashed passwords.

See https://mosquitto.org/ for more information.