nushell/crates/nu-command
Douglas eedf833b6f
Send both 2J and 3J on clear (#14181)
Fixes #14176

# Description

Since the Linux `/usr/bin/clear` binary doesn't exhibit the issue in
#14176, I checked to see what ANSI escapes it is emitting:

```nu
nu -c '^clear; "111\n222\n333"' | less
# or
bash -c 'clear -x; echo -e "111\n222\n333"' | less
```

Both show the same thing:

```
ESC[HESC[2JESC[3J111
222
333
(END)
```

This is the equivalent of:

```nu
$"(ansi home)(ansi clear_entire_screen)(ansi clear_entire_screen_plus_buffer)111\n222\n333"
```

However, our internal `clear` is sending only the Home and 3J. While
this *should*, in theory, work, it's (a) clear that it doesn't, and (b)
`/usr/bin/clear` seemingly knows this and already has the solution (or
at least workaround). From looking at the `ncurses` source, it appears
it is getting this information from the terminal capabilities. That
said, support for `2J` and `3J` is fairly universal, and it's what we
send in `clear` and `clear --keep-scrollback` anyway, so there's no harm
AFAICT in sending both like `/usr/bin/clear` does.

Also tested and fixes the issue on Windows. Note that PowerShell
`Clear-Host` also did not have the issue.

Side-note: It's interesting that on Tmux, which doesn't support 2J and
3J, that `/usr/bin/clear` knows this and doesn't send those codes,
sending just an escape-[J instead. However, Nushell's `clear`, of
course, isn't checking terminal capabilities, and is continuing to send
the unsupported codes. Fortunately this doesn't appear to cause any
issues on Tmux.

# User-Facing Changes

None, AFAICT - Bugfix only.

# Tests + Formatting

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting

N/A
2024-10-28 06:42:18 -05:00
..
src Send both 2J and 3J on clear (#14181) 2024-10-28 06:42:18 -05:00
tests Add metadata on open --raw with bytestreams (#14141) 2024-10-23 16:50:15 -05:00
Cargo.toml Bump to 0.99.2 (#14136) 2024-10-20 23:12:41 +02:00
LICENSE Fix rest of license year ranges (#8727) 2023-04-04 09:03:29 +12:00
README.md Add top-level crate documentation/READMEs (#12907) 2024-07-14 10:10:41 +02:00

This crate contains the majority of our commands

We allow ourselves to move some of the commands in nu-command to nu-cmd-* crates as needed.

Internal Nushell crate

This crate implements components of Nushell and is not designed to support plugin authors or other users directly.