added some builtincommands

Author: exilonium

src/main.rs

@@ -1,13 +1,61 @@
 #[allow(unused_imports)]
 use std::io::{self, Write};
 
+const BUILT_IN_COMMANDS: [&str;3] = ["echo","exit","type"];
+
+enum Command{
+    ExitCommand,
+    EchoCommand {display_string:String},
+    TypeCommand {command_name: String},
+    CommandNotFound,
+}
+
+impl Command{
+    fn from_input(input:&str) -> Self {
+        let input=input.trim();
+        if input == "exit" || input == "exit 0" {
+            return Self::ExitCommand;
+        };
+        if let Some(pos) = input.find("echo ") {
+            if pos ==0{
+                return Self::EchoCommand{
+                    display_string: input["echo ".len()..].to_string(),
+                };
+            }
+        }
+        if let Some(pos) = input.find("type "){
+            if pos==0 {
+                return Self::TypeCommand{
+                    command_name: input["type ".len()..].to_string(),
+                };
+            }
+        }
+        Self::CommandNotFound // we are returning this value
+    }
+
+}
+
 fn main() {
     loop{
         print!("$ ");
         io::stdout().flush().unwrap();
 
-        let mut command = String::new();
-        io::stdin().read_line(&mut command).unwrap();
-        println!("{}: command not found",command.trim());
+        let mut input = String::new();
+        io::stdin().read_line(&mut input).unwrap();
+        
+        //implementing internal built_in_commands
+        let command = Command::from_input(&input);
+        match command{
+            Command::ExitCommand => break,
+            Command::EchoCommand {display_string} => println!("{}", display_string),
+            Command::TypeCommand {command_name} => {
+                if BUILT_IN_COMMANDS.contains(&command_name.as_str()){
+                    println!("{} is a shell builtin",command_name);
+                } else {
+                    println!("{}: command not found", command_name);
+                }
+            },
+            Command::CommandNotFound => println!("{} bruh command not found", input.trim()),
+        }
     }
 }