simple nu scripts return partial line

[kiil]

Describe the bug

When I run a simple nu script from within bash, sh or zsh, it will return a partial line.

How to reproduce

Try to run an executable file from a zsh shell containing these lines:

#!/usr/bin/env nu
'test'

The output will be

test%

I believe the '%' is a way for zsh to indicate a partial line. In sh the output from the script is simply put on the same line as the next prompt.

Expected behavior

I expected nu to simply give the output
test
on its own separate line, ie include a newline character in its output.

Screenshots

No response

Configuration

key	value
version	0.74.0
branch
commit_hash
build_os	linux-x86_64
build_target	x86_64-unknown-linux-gnu
rust_version	rustc 1.66.0 (69f9c33d7 2022-12-12) (Arch Linux rust 1:1.66.0-1)
cargo_version	cargo 1.66.0
pkg_version	0.74.0
build_time	2023-01-12 11:46:18 +01:00
build_rust_channel	release
features	database, dataframe, default, trash, which, zip
installed_plugins

Additional context

The partial line / missing new line character problem causes nu scripts to malfunction in some contexts.

[kiil]

echo test

results in the same partial line / missing end of line character / missing new line character problem when a simple script is interpreted by nu in another shell.

There is an easy way to avoid the problem. Simply ending the simple script with an empty closure like so:

#!/usr/bin/env nu
'test'
{}

But I think it should work without that, or maybe there is something I do not understand.

[fdncred]

Thanks for the issue. Your script works as expected from within nushell. I want to say the expected behavior is to always trim trailing newlines, but I could be wrong. It's been a while since I looked at that code.

[kiil]

I ran into the issue because the nwg-wrapper python script seems to strip the last character of the script file that it is fed as input, and when there is no trailing newline, it just seems to eat whatever other character that is last on the last line of the file.

So I guess the assumption of some other scripts is that a script used as input retains its newline after being run by the shell in question.

For me the solution is just to end the script file with {}

[kiil]

So, if I run this inside zsh but with fish interpreting

#!/usr/bin/env fish
echo test

There is a newline included in the output, hence there is not the partial line problem.

So maybe the "standard" is to include a newline character in the output,, but that in itself does not mean that nushell also has to do that. Because, why add a character that was not there.

[sholderbach]

This is certainly one of those places where nu's richer data model that tries to keep most information faithfully (like just the string) collides with the customary traditions of POSIX shells that paper over some undefined cases.

We should make sure we are a good citizen while not breaking some of the inherent consistency (or the ambition thereof) inside nushell.

[kiil]

The more I think about it, the more it seems the way nushell does it now, is the right way.

[fdncred]

Let's close this for now then. We can always open it back up, if we change our minds.

[sholderbach]

One argument for it is that we strip trailing line endings from external commands in subexpressions (I think only there #7156)

But we also have other areas were our special behavior leaks unexpectedly through our pretty printing etc. (e.g. #7615, ANSI in find)