cat

So, what’s “Here Docs”? Well, if you don’t know what it is yet, then hopefully by the time you finish reading this post you’ll know what it is. Here docs or here documents is a special block code, of which we can use a form of I/O redirection to feed a command list to an interactive program, e.g. cat or the ex text editor according to [1]. Here is an example where a file basic-ingress....

You’ve been using Linux for a while, so you must have seen or used this command before: cat. It’s used to concatenate files and print on the standard output. But do you know there is another command spelled it reversed tac? tac is like cat, but print files in reverse. Here is an example which cat could be handy. I need to print out the last login user in reverse. (By the default, it prints the last login first....