dash:tldr:9c4a1

This command is a pipeline command that consists of two parts:

1. ${echo "echo 'dash is executed'"}: This is using command substitution syntax in the form of ${...}. It is attempting to execute a command within the backticks or $(). However, the use of echo command here is redundant, as it is effectively just echoing the provided string "echo 'dash is executed'". So, this part is equivalent to simply "echo 'dash is executed'".

2. | dash: The output of the command substitution is then piped (|) to the dash command. dash is a Unix/Unix-like shell, specifically the Debian Almquist Shell. By piping the output of the previous command to dash, it will attempt to interpret and execute the provided string "echo 'dash is executed'" as a command in the dash shell.

In summary, the command tries to execute the string "echo 'dash is executed'" using the dash shell. It should print the message "dash is executed" to the standard output.