xcowsay:tldr:83590

The command "xcowsay" is a program that displays a graphical image of a cow on your screen along with a speech bubble containing a message. It is a variation of the well-known "cowsay" program.

In this specific command, the message inside the speech bubble is "${hello, world}". The double quotes around the message ensure that the entire message is considered as a single string by the command.

The use of "${...}" indicates that the message is a variable or expression that needs to be expanded or evaluated. However, in this case, the message "${hello, world}" is written as it is, without any variable substitution or evaluation, because the text inside is not a recognized variable or expression.

So, when you execute the command "xcowsay "${hello, world}"", a graphical cow image will appear on your screen with a speech bubble containing the text "${hello, world}".