let start open anything and everything (#7580)

# Description

Fixes #7546 's request. I'm unsure, so hopefully someone in charge of
design can chip in.

# User-Facing Changes

`open` now opens directories in the default file manager.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/src/dataframe/eager/mod.rs

@@ -30,6 +30,7 @@ mod with_column;
 
 use nu_protocol::engine::StateWorkingSet;
 
+pub use self::open::OpenDataFrame;
 pub use append::AppendDF;
 pub use columns::ColumnsDF;
 pub use drop::DropDF;
@@ -43,7 +44,6 @@ pub use get::GetDF;
 pub use last::LastDF;
 pub use list::ListDF;
 pub use melt::MeltDF;
-pub use open::OpenDataFrame;
 pub use query_df::QueryDf;
 pub use rename::RenameDF;
 pub use sample::SampleDF;

crates/nu-command/src/default_context.rs

@@ -275,6 +275,7 @@ pub fn create_default_context() -> EngineState {
             Mkdir,
             Mv,
             Open,
+            Start,
             Rm,
             Save,
             Touch,

crates/nu-command/src/filesystem/mod.rs

@@ -8,10 +8,12 @@ mod mv;
 mod open;
 mod rm;
 mod save;
+mod start;
 mod touch;
 mod util;
 mod watch;
 
+pub use self::open::Open;
 pub use cd::Cd;
 pub use cd_query::query;
 pub use cp::Cp;
@@ -19,9 +21,9 @@ pub use glob::Glob;
 pub use ls::Ls;
 pub use mkdir::Mkdir;
 pub use mv::Mv;
-pub use open::Open;
 pub use rm::Rm;
 pub use save::Save;
+pub use start::Start;
 pub use touch::Touch;
 pub use util::BufferedReader;
 pub use watch::Watch;

crates/nu-command/src/filesystem/start.rs

@@ -0,0 +1,103 @@
+use nu_engine::CallExt;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type, Value,
+};
+use std::path::Path;
+
+#[derive(Clone)]
+pub struct Start;
+
+impl Command for Start {
+    fn name(&self) -> &str {
+        "start"
+    }
+
+    fn usage(&self) -> &str {
+        "Open a folder or file in the default application or viewer."
+    }
+
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["load", "folder", "directory", "run", "open"]
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("start")
+            .input_output_types(vec![(Type::Nothing, Type::Any), (Type::String, Type::Any)])
+            .optional("filepath", SyntaxShape::Filepath, "the filepath to open")
+            .category(Category::FileSystem)
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let path = call.opt::<Spanned<String>>(engine_state, stack, 0)?;
+
+        let path = {
+            if let Some(path_val) = path {
+                Some(Spanned {
+                    item: nu_utils::strip_ansi_string_unlikely(path_val.item),
+                    span: path_val.span,
+                })
+            } else {
+                path
+            }
+        };
+
+        let path = if let Some(path) = path {
+            path
+        } else {
+            // Collect a filename from the input
+            match input {
+                PipelineData::Value(Value::Nothing { .. }, ..) => {
+                    return Err(ShellError::MissingParameter(
+                        "needs filename".to_string(),
+                        call.head,
+                    ))
+                }
+                PipelineData::Value(val, ..) => val.as_spanned_string()?,
+                _ => {
+                    return Err(ShellError::MissingParameter(
+                        "needs filename".to_string(),
+                        call.head,
+                    ));
+                }
+            }
+        };
+        let path_no_whitespace = &path.item.trim_end_matches(|x| matches!(x, '\x09'..='\x0d'));
+        let path = Path::new(path_no_whitespace);
+
+        open::that(path)?;
+        Ok(PipelineData::Empty)
+    }
+
+    fn examples(&self) -> Vec<nu_protocol::Example> {
+        vec![
+            Example {
+                description: "Open a text file with the default text editor",
+                example: "start file.txt",
+                result: None,
+            },
+            Example {
+                description: "Open an image with the default image viewer",
+                example: "start file.jpg",
+                result: None,
+            },
+            Example {
+                description: "Open the current directory with the default file manager",
+                example: "start .",
+                result: None,
+            },
+            Example {
+                description: "Open a pdf with the default pdf viewer",
+                example: "start file.pdf",
+                result: None,
+            },
+        ]
+    }
+}