A one liner does not mean "one line of source code in a file", it means "a single shell statement". That's why the Ruby command is prefixing them all. I routinely write 10-20 statement Perl one-liners at work for one off things.

For example, just yesterday it was to parse a log, grep for specific lines, pull out a time and a number per line, display name, number, and some number of characters afterwards as a quick abnd dirty graph of the magnitude to make it obvious if there were major outliers and to try to see trends over time. Still a one-liner.

In theory, couldn’t you then compile a Rails app into a one-liner? (Seems the max line length varies, but is at least hundreds of thousands of characters in most OSes)

You could, but it would be stupid to do so if it wasn't a trivial app, since nobody wants to support something like that, even if it's lifetime is measured in minutes or hours. It's a one-liner, just a pointless one.

That said, if rails has a super simple default startup that could serve a file, then it might be useful to start that as a one liner in select circumstances.

Rails has generators for that. Invaluable for greenfielding projects in an iterative manner. Blow everything away and recreate with a single command.

https://guides.rubyonrails.org/generators.html

nobody wants to support weird looking one-liners either

Sure, but then you could refactor most programs into "one line" (similar to what another commenter pointed out). I was expecting more of a functional piping or chaining style as opposed to distinct statements and defining local variables.

You're not being pedantic. The term "one-liner" is a misnomer. In many languages, whether or not a program can fit on a single line is a pointless metric, since a program can be rewritten into a single line (e.g. with semicolons or commas). People use the term "one-liner" as if it meant "concise code" which isn't necessarily true. It would be more accurate to just say "concise code".

I would expand on that and say 'concise code executed by directly invoking the parser in a shell-like environment using special flags such as a,n,p and e.'

Guess you could replace ; with && for many of them. More typing though.