Initial commit for fern

src/builtin/cd.rs

@@ -0,0 +1,15 @@
+use crate::{parse::parse::{Node, NdRule}, prelude::*};
+
+pub fn cd(node: Node, shenv: &mut ShEnv) -> ShResult<()> {
+	let rule = node.into_rule();
+	if let NdRule::Command { argv, redirs: _ } = rule {
+		let mut argv_iter = argv.into_iter();
+		argv_iter.next(); // Ignore 'cd'
+		let dir_raw = argv_iter.next().map(|arg| arg.to_string()).unwrap_or(std::env::var("HOME")?);
+		let dir = PathBuf::from(&dir_raw);
+		std::env::set_current_dir(dir)?;
+		shenv.vars_mut().export("PWD",&dir_raw);
+		shenv.set_code(0);
+	}
+	Ok(())
+}