uv run: List available scripts when a script is not specified (#7687)

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>
## Summary

This PR adds the ability to list available scripts in the environment
when `uv run` is invoked without any arguments.
It somewhat mimics the behavior of `rye run` command
(See https://rye.astral.sh/guide/commands/run).

This is an attempt to fix #4024.

## Test Plan

I added test cases. The CI pipeline should pass.

### Manuel Tests

```shell
❯ uv run
Provide a command or script to invoke with `uv run <command>` or `uv run script.py`.

The following scripts are available:

normalizer
python
python3
python3.12

See `uv run --help` for more information.
```

---------

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>
Co-authored-by: Zanie Blue <contact@zanie.dev>

crates/uv-cli/src/lib.rs

@@ -2543,7 +2543,7 @@ pub struct RunArgs {
     /// If the path to a Python script (i.e., ending in `.py`), it will be
     /// executed with the Python interpreter.
     #[command(subcommand)]
-    pub command: ExternalCommand,
+    pub command: Option<ExternalCommand>,
 
     /// Run with the given packages installed.
     ///

crates/uv-fs/Cargo.toml

@@ -29,6 +29,12 @@ tempfile = { workspace = true }
 tracing = { workspace = true }
 urlencoding = { workspace = true }
 
+[target.'cfg(target_os = "windows")'.dependencies]
+winsafe = { workspace = true }
+
+[target.'cfg(any(unix, target_os = "wasi", target_os = "redox"))'.dependencies]
+rustix = { workspace = true }
+
 [target.'cfg(windows)'.dependencies]
 junction = { workspace = true }
 

crates/uv-fs/src/lib.rs

@@ -8,6 +8,7 @@ pub use crate::path::*;
 
 pub mod cachedir;
 mod path;
+pub mod which;
 
 /// Reads data from the path and requires that it be valid UTF-8 or UTF-16.
 ///

crates/uv-python/src/which.rs → crates/uv-fs/src/which.rs

@@ -3,7 +3,7 @@ use std::path::Path;
 /// Check whether a path in PATH is a valid executable.
 ///
 /// Derived from `which`'s `Checker`.
-pub(crate) fn is_executable(path: &Path) -> bool {
+pub fn is_executable(path: &Path) -> bool {
     #[cfg(any(unix, target_os = "wasi", target_os = "redox"))]
     {
         if rustix::fs::access(path, rustix::fs::Access::EXEC_OK).is_err() {

crates/uv-python/Cargo.toml

@@ -53,12 +53,8 @@ tracing = { workspace = true }
 url = { workspace = true }
 which = { workspace = true }
 
-[target.'cfg(any(unix, target_os = "wasi", target_os = "redox"))'.dependencies]
-rustix = { workspace = true }
-
 [target.'cfg(target_os = "windows")'.dependencies]
 windows-sys = { workspace = true }
-winsafe = { workspace = true }
 windows-registry = { workspace = true }
 windows-result = { workspace = true }
 

crates/uv-python/src/discovery.rs

@@ -10,6 +10,7 @@ use tracing::{debug, instrument, trace};
 use which::{which, which_all};
 
 use uv_cache::Cache;
+use uv_fs::which::is_executable;
 use uv_fs::Simplified;
 use uv_pep440::{Prerelease, Version, VersionSpecifier, VersionSpecifiers};
 use uv_warnings::warn_user_once;
@@ -27,7 +28,6 @@ use crate::virtualenv::{
     conda_prefix_from_env, virtualenv_from_env, virtualenv_from_working_dir,
     virtualenv_python_executable,
 };
-use crate::which::is_executable;
 use crate::{Interpreter, PythonVersion};
 
 /// A request to find a Python installation.

crates/uv-python/src/lib.rs

@@ -37,7 +37,6 @@ mod python_version;
 mod target;
 mod version_files;
 mod virtualenv;
-mod which;
 
 #[cfg(not(test))]
 pub(crate) fn current_dir() -> Result<std::path::PathBuf, std::io::Error> {

crates/uv/src/commands/project/run.rs

@@ -18,9 +18,11 @@ use uv_configuration::{
     Concurrency, DevMode, EditableMode, ExtrasSpecification, InstallOptions, SourceStrategy,
 };
 use uv_distribution::LoweredRequirement;
+use uv_fs::which::is_executable;
 use uv_fs::{PythonExt, Simplified};
 use uv_installer::{SatisfiesResult, SitePackages};
 use uv_normalize::PackageName;
+
 use uv_python::{
     EnvironmentPreference, Interpreter, PythonDownloads, PythonEnvironment, PythonInstallation,
     PythonPreference, PythonRequest, PythonVariant, PythonVersionFile, VersionRequest,
@@ -51,7 +53,7 @@ use crate::settings::ResolverInstallerSettings;
 pub(crate) async fn run(
     project_dir: &Path,
     script: Option<Pep723Script>,
-    command: RunCommand,
+    command: Option<RunCommand>,
     requirements: Vec<RequirementsSource>,
     show_resolution: bool,
     locked: bool,
@@ -751,6 +753,73 @@ pub(crate) async fn run(
         .as_ref()
         .map_or_else(|| &base_interpreter, |env| env.interpreter());
 
+    // Check if any run command is given.
+    // If not, print the available scripts for the current interpreter.
+    let Some(command) = command else {
+        writeln!(
+            printer.stdout(),
+            "Provide a command or script to invoke with `uv run <command>` or `uv run <script>.py`.\n"
+        )?;
+
+        #[allow(clippy::map_identity)]
+        let commands = interpreter
+            .scripts()
+            .read_dir()
+            .ok()
+            .into_iter()
+            .flatten()
+            .map(|entry| match entry {
+                Ok(entry) => Ok(entry),
+                Err(err) => {
+                    // If we can't read the entry, fail.
+                    // This could be a symptom of a more serious problem.
+                    warn!("Failed to read entry: {}", err);
+                    Err(err)
+                }
+            })
+            .collect::<Result<Vec<_>, _>>()?
+            .into_iter()
+            .filter(|entry| {
+                entry
+                    .file_type()
+                    .is_ok_and(|file_type| file_type.is_file() || file_type.is_symlink())
+            })
+            .map(|entry| entry.path())
+            .filter(|path| is_executable(path))
+            .map(|path| {
+                if cfg!(windows) {
+                    // Remove the extensions.
+                    path.with_extension("")
+                } else {
+                    path
+                }
+            })
+            .map(|path| {
+                path.file_name()
+                    .unwrap_or_default()
+                    .to_string_lossy()
+                    .to_string()
+            })
+            .filter(|command| {
+                !command.starts_with("activate") && !command.starts_with("deactivate")
+            })
+            .sorted()
+            .collect_vec();
+
+        if !commands.is_empty() {
+            writeln!(
+                printer.stdout(),
+                "The following commands are available in the environment:\n"
+            )?;
+            for command in commands {
+                writeln!(printer.stdout(), "- {command}")?;
+            }
+        }
+        let help = format!("See `{}` for more information.", "uv run --help".bold());
+        writeln!(printer.stdout(), "\n{help}")?;
+        return Ok(ExitStatus::Error);
+    };
+
     debug!("Running `{command}`");
     let mut process = command.as_command(interpreter);
 

crates/uv/src/lib.rs

@@ -133,7 +133,7 @@ async fn run(cli: Cli) -> Result<ExitStatus> {
     // Parse the external command, if necessary.
     let run_command = if let Commands::Project(command) = &*cli.command {
         if let ProjectCommand::Run(uv_cli::RunArgs {
-            command,
+            command: Some(command),
             module,
             script,
             ..
@@ -1239,9 +1239,6 @@ async fn run_project(
                 )
                 .collect::<Vec<_>>();
 
-            // Given `ProjectCommand::Run`, we always expect a `RunCommand` to be present.
-            let command = command.expect("run command is required");
-
             Box::pin(commands::run(
                 project_dir,
                 script,

crates/uv/tests/run.rs

@@ -198,6 +198,74 @@ fn run_args() -> Result<()> {
     Ok(())
 }
 
+/// Run without specifying any argunments.
+/// This should list the available scripts.
+#[test]
+fn run_no_args() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! { r#"
+        [project]
+        name = "foo"
+        version = "1.0.0"
+        requires-python = ">=3.8"
+        dependencies = []
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+        "#
+    })?;
+
+    // Run without specifying any argunments.
+    #[cfg(not(windows))]
+    uv_snapshot!(context.filters(), context.run(), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+    Provide a command or script to invoke with `uv run <command>` or `uv run <script>.py`.
+
+    The following commands are available in the environment:
+
+    - python
+    - python3
+    - python3.12
+
+    See `uv run --help` for more information.
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + foo==1.0.0 (from file://[TEMP_DIR]/)
+    "###);
+
+    #[cfg(windows)]
+    uv_snapshot!(context.filters(), context.run(), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+    Provide a command or script to invoke with `uv run <command>` or `uv run <script>.py`.
+
+    The following commands are available in the environment:
+    
+    - pydoc
+    - python
+    - pythonw
+
+    See `uv run --help` for more information.
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + foo==1.0.0 (from file://[TEMP_DIR]/)
+    "###);
+
+    Ok(())
+}
+
 /// Run a PEP 723-compatible script. The script should take precedence over the workspace
 /// dependencies.
 #[test]

docs/reference/cli.md

@@ -65,7 +65,7 @@ Arguments following the command (or script) are not interpreted as arguments to
 <h3 class="cli-reference">Usage</h3>
 
 ```
-uv run [OPTIONS] <COMMAND>
+uv run [OPTIONS] [COMMAND]
 ```
 
 <h3 class="cli-reference">Options</h3>