printf:tldr:b24f6

The command printf "${%s\n}" "${Hello world}" is a combination of the printf command and various formatting strings and arguments.

Here's a breakdown of the command:

1. printf: It is a command-line utility used to format and print text. It takes one or more arguments, including a formatting string, and prints the formatted output to the console.

2. "${%s\n}": This is the formatting string passed to printf. It specifies how the provided arguments should be formatted and displayed. %s is a placeholder for a string, and \n represents a newline character.

3. "${Hello world}": This is the argument passed to printf. In this case, it is the text "Hello world" enclosed in double quotes. The double quotes are used to preserve the space between the two words as a single argument.

The purpose of this command seems to be to print the string "Hello world" with a newline character after it. However, the formatting string ${%s\n} is incorrect syntax. A valid formatting string could be "${%s}\n", which would substitute the argument ${Hello world} into the string and append a newline character to it.