chpasswd:tldr:d7753

This command is used to change the password of a user account on a Unix or Linux system.

Let's break down the command step by step:

1. printf "${username}:${new_password}": printf is a command used to format and print data. Here, it is used to print a string which consists of the username variable followed by a colon (:) and the new_password variable. The ${variable_name} syntax is used to represent the value of a variable.

2. |: This is a pipe operator that takes the output of the command on the left side and passes it as input to the command on the right side. In this case, the output of the printf command is passed as input to the sudo chpasswd command.

3. sudo chpasswd: sudo is a command that allows a user with appropriate permissions to execute a command as another user (usually the root user). chpasswd is a command used to update password entries in the system password file. By using sudo before chpasswd, the command is executed with root privileges.

In summary, this command takes the username and new_password variables, combines them with a colon separator, and passes them to chpasswd with root privileges using sudo. This effectively changes the password of the specified user account.