For additional clarification, `echo` doesn’t read from stdin, so `… | echo xyz` doesn’t do what you probably assume. Try running `echo a | echo b` and you’ll see that only “b” is printed. That’s because `echo b` doesn’t read the “a” sent to it on stdin (and also doesn’t print it).

If you want a program to read from stdin and write to stdout, you can use the `cat`, e.g. `echo a | cat` will print “a”.

Lastly, be aware that `echo` is usually a shell builtin that functions like `print`. I’m not sure of all the ways that it might behave differently, but something to be aware of (that it’s not a child process like `cat`).