Item — HN Reader

I think you should take a deep breath and read this updated FAQ:

https://refp.se/articles/your-shell-and-the-magic-colon#why-...

I am not asking anyone to put this in production, it is a tongue-in-cheek/cute way of explaining/showing what the null-command _can_ do, not what it _must_ do.

No, any distro that stopped shipping entities mentioned to use only null-command variants.. well, I'd save whatever your end goal is to a meeting with them.

Just enjoy the article for what it is — a piece of trivia.

Best Regards, Filip Roséen - refp

1 comments

I understand; it's just "here are these cool, obscure things you can do with the colon". I had no idea it was supposed to be "here are these cool, obscure things yuo can do with the colon, carefully coded to work on numerous POSIX-like shells that are in widespread use.

To me, it's "cool" that you can just do "< test-file && echo exists", on a shell whose developers haven't decided to imbue a whole bunch of new requirements into redirection. It's completely legit to note that the existence test is not coming from the : command, but from redirections, and redirections can be set up without a command. The : is only there to work around shell quirks.

For decades, I used "> file" to truncate files to zero length, never with a colon command; the example makes it look as if the colon is required in order for the command line to be valid and for the effect to take place.

BTW I noticed that zsh not only does the cat-like dumping to stdout in non-interactive mode, but it also does the redirection to the pager!!! So if you drop that test into a non-interactive script, and it finds an existing file, if that script is run in a terminal session, it will pause for input.