implement exec for unix platforms (#2495)

crates/nu-cli/src/cli.rs

@@ -79,6 +79,7 @@ pub fn create_default_context(
 
         context.add_commands(vec![
             // System/file operations
+            whole_stream_command(Exec),
             whole_stream_command(Pwd),
             whole_stream_command(Ls),
             whole_stream_command(Du),

crates/nu-cli/src/commands.rs

@@ -36,6 +36,7 @@ pub(crate) mod each;
 pub(crate) mod echo;
 pub(crate) mod enter;
 pub(crate) mod every;
+pub(crate) mod exec;
 pub(crate) mod exit;
 pub(crate) mod first;
 pub(crate) mod format;
@@ -165,6 +166,7 @@ pub(crate) use clear::Clear;
 pub(crate) mod touch;
 pub(crate) use enter::Enter;
 pub(crate) use every::Every;
+pub(crate) use exec::Exec;
 pub(crate) use exit::Exit;
 pub(crate) use first::First;
 pub(crate) use format::Format;

crates/nu-cli/src/commands/exec.rs

@@ -0,0 +1,87 @@
+use crate::commands::WholeStreamCommand;
+use crate::context::CommandRegistry;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{Signature, SyntaxShape};
+use nu_source::Tagged;
+use std::path::PathBuf;
+
+pub struct Exec;
+
+#[derive(Deserialize)]
+pub struct ExecArgs {
+    pub command: Tagged<PathBuf>,
+    pub rest: Vec<Tagged<String>>,
+}
+
+#[async_trait]
+impl WholeStreamCommand for Exec {
+    fn name(&self) -> &str {
+        "exec"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("exec")
+            .required("command", SyntaxShape::Path, "the command to execute")
+            .rest(SyntaxShape::Pattern, "any additional arguments for command")
+    }
+
+    fn usage(&self) -> &str {
+        "Execute command"
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        exec(args, registry).await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Execute 'ps aux'",
+                example: "exec ps aux",
+                result: None,
+            },
+            Example {
+                description: "Execute 'nautilus'",
+                example: "exec nautilus",
+                result: None,
+            },
+        ]
+    }
+}
+
+#[cfg(unix)]
+async fn exec(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+    use std::os::unix::process::CommandExt;
+    use std::process::Command;
+
+    let registry = registry.clone();
+    let name = args.call_info.name_tag.clone();
+    let (args, _): (ExecArgs, _) = args.process(&registry).await?;
+
+    let mut command = Command::new(args.command.item);
+    for tagged_arg in args.rest {
+        command.arg(tagged_arg.item);
+    }
+
+    let err = command.exec(); // this replaces our process, should not return
+
+    Err(ShellError::labeled_error(
+        "Error on exec",
+        format!("{}", err),
+        &name,
+    ))
+}
+
+#[cfg(not(unix))]
+async fn exec(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+    Err(ShellError::labeled_error(
+        "Error on exec",
+        "exec is not supported on your platform",
+        &args.call_info.name_tag,
+    ))
+}