title: "cat a | cat b" ignoring contents of a
body: <p>The formal definition of pipe states that the STDOUT of the left file will be immediately piped to the STDIN of the right file.I have two files, <code>hello.txt</code> and <code>human.txt</code>.  <code>cat hello.txt</code> returns <code>Hello</code> and <code>cat human.txt</code> returns <code>I am human</code>.Now if I do <code>cat hello.txt | cat human.txt</code>, shouldn't that return <code>Hello I am human</code>?Instead I'm seeing <code>command not found</code>.I am new to shell scripting.Can someone explain? </p>