feat: add support for 'cd' command in REPL loop

src/main.rs

@@ -1,9 +1,7 @@
-use std::{io::{stdin, stdout, Write}, process::Command};
+use std::{env, io::{stdin, stdout, Write}, path::Path, process::Command};
 
 fn main(){
     loop {
-        // use the `>` character as the prompt
-        // need to explicitly flush this to ensure it prints before read_line
         print!("> ");
         stdout().flush();
 
@@ -14,13 +12,23 @@ fn main(){
         let command = parts.next().unwrap();
         let args = parts;
 
+        match command {
+            "cd" => {
+                // default to '/' as new directory if one was not provided
+                let new_dir = args.peekable().peek().map_or("/", |x| *x);
+                let root = Path::new(new_dir);
+                if let Err(e) = env::set_current_dir(&root) {
+                    eprintln!("{}", e);
+                }
+            },
+            command => {
                 let mut child = Command::new(command)
                     .args(args)
                     .spawn()
                     .unwrap();
 
-        // don't accept another command until this one completes
                 child.wait();
             }
         }
-
+    }
+}