feat: add new shell command "eval"

shell/src/built_in/eval.rs

@@ -0,0 +1,17 @@
+use crate::built_in::Action;
+use std::process::Command;
+
+pub fn eval(arguments: Vec<&str>) -> Action {
+    if arguments.len() < 1 {
+        panic!("eval expects **one or more** arguments");
+    }
+
+    let output = Command::new(arguments[0]).args(&arguments[1..]).spawn();
+    match output {
+        Ok(mut output) => {
+            output.wait().expect("failed to wait for process exit");
+        }
+        Err(err) => println!("{:?}", err)
+    }
+    Action::Nothing
+}

shell/src/built_in/mod.rs

@@ -1,16 +1,19 @@
 mod cd;
 mod exit;
+mod eval;
 
 #[derive(Debug)]
 pub enum Action {
     Exit,
     ChangeDirectory(String),
+    Nothing
 }
 
 fn get_function(command: String) -> Option<fn(Vec<&str>) -> Action> {
     let registry = [
         ("exit", exit::exit as fn(Vec<&str>) -> Action),
         ("cd", cd::cd as fn(Vec<&str>) -> Action),
+        ("eval", eval::eval as fn(Vec<&str>) -> Action)
     ];
     let mut function: Option<fn(Vec<&str>) -> Action> = None;