john:tldr:a8f49
This command is using the program called "john," which is a password cracking tool. The command is attempting to crack passwords stored in a text file specified by the variable "${path-to-hashes-txt}".
The format of the text file should contain the hashed passwords, typically in the format "username:hash", where the hash represents the encrypted form of the password. The file should include one password entry per line.
The "--rules" flag is used to enable the application of a set of rules to the password cracking process. These rules can help in generating variations of the passwords and increase the chances of finding a match. By default, John the Ripper (john) does not apply any rules.
The actual path to the text file containing the hashed passwords needs to be specified in place of "${path-to-hashes-txt}" for the command to work properly.