diff --git a/src/command.rs b/src/command.rs
index c872f2a..f2d968e 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -105,14 +105,17 @@ pub fn help(pargs: &mut Arguments) {
 pub fn attach(pargs: &mut Arguments) {
 	util::prevent_nest();
 
+	//	get optional flags
 	let read_only = pargs.contains(["-r", "--readonly"]);
 	let detach_other = pargs.contains(["-d", "--detach"]);
 
+	//	get target and error out if not provided
 	let args = pargs.clone().finish();
-
+	if args.len() < 1 { error::missing_target(); }
 	let target = args.get(0).unwrap().to_string_lossy();
 	let window = args.get(1);
 
+	//	focus window if provided
 	if window.is_some() {
 		let target = window.unwrap().to_string_lossy();
 		let tmux = TmuxCommand::new();
@@ -122,6 +125,7 @@ pub fn attach(pargs: &mut Arguments) {
 			.output().ok();
 	}
 
+	//	command
 	let tmux = TmuxCommand::new();
 	let exists = tmux
 		.has_session()
@@ -131,6 +135,7 @@ pub fn attach(pargs: &mut Arguments) {
 
 	let mut attach = tmux.attach_session();
 
+	//	handle optional flags
 	if read_only { attach.read_only(); }
 	if detach_other { attach.detach_other(); }
 
@@ -140,10 +145,12 @@ pub fn attach(pargs: &mut Arguments) {
 }
 
 pub fn detach(pargs: &mut Arguments) {
+	//	get target and error out if not provided
 	let args = pargs.clone().finish();
-
+	if args.len() < 1 { error::missing_target(); }
 	let target = args.get(0).unwrap().to_string_lossy();
 
+	//	command
 	let tmux = TmuxCommand::new();
 	let exists = tmux
 		.has_session()
@@ -158,11 +165,15 @@ pub fn detach(pargs: &mut Arguments) {
 }
 
 pub fn has(pargs: &mut Arguments) {
+	//	get optional flag
 	let quiet = pargs.contains(["-q", "--quiet"]);
 
+	//	get target and error out if not provided
 	let args = pargs.clone().finish();
+	if args.len() < 1 { error::missing_target(); }
 	let target = args.get(0).unwrap().to_string_lossy();
 
+	//	command
 	let tmux = TmuxCommand::new();
 	let exists = tmux
 		.has_session()
@@ -171,19 +182,25 @@ pub fn has(pargs: &mut Arguments) {
 
 	let success = exists.success();
 
+	//	handle optional flag
+	//	inverted; print text if NOT quiet
 	if !quiet { println!("session \"{target}\" {}.", if success { "exists" } else { "does not exist" }); }
 
+	//	exit codes for scripts to use
 	exit( if success { 0 } else { 1 });
 }
 
 pub fn list() {
+	//	get session list
 	let sessions = util::get_sessions().unwrap_or(Vec::new());
 
+	//	handle empty case
 	if sessions.len() == 0 {
 		println!("no sessions");
 		return;
 	}
 
+	//	iterate over pretty print
 	println!("sessions:");
 	for session in sessions.into_iter() {
 		let group = session.group.unwrap_or("[untitled]".to_string());
@@ -206,11 +223,17 @@ pub fn list() {
 pub fn new(pargs: &mut Arguments) {
 	use pico_args::Error;
 
+	//	show nest message
 	util::prevent_nest();
 
+	//	get optional flag
 	let target_dir: Result<String, Error> = pargs.value_from_str(["-t", "--target"]);
 
+	//	get target and error out if not provided
 	let args = pargs.clone().finish();
+	if args.len() < 1 { error::missing_target(); }
+
+	//	get target session and optional command
 	let title = args.get(0).unwrap().to_string_lossy();
 	let command = args.get(1);
 
diff --git a/src/error.rs b/src/error.rs
index 81003c7..d33754e 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,22 +1,32 @@
 use std::process::exit;
 
+///	no subcommand that matches user input; code 1
 pub fn no_subcommand(subcommand: String) {
 	println!("remux: no command match for \"{subcommand}\"");
 	exit(1);
 }
 
+///	target session not found; code 2
 pub fn no_target(target: String) {
 	println!("remux: no session \"{target}\" exists");
 	exit(2);
 }
+///	no sessions exist; code 2
 pub fn no_sessions() {
 	println!("remux: no sessions running");
 	println!("use 'remux n <title>' to create a new session");
 	exit(2);
 }
 
+///	help topic doesn't exist; code 3
 pub fn no_help(topic: String) {
 	println!("remux: no help for \"{topic}\"");
 	exit(3);
 }
 
+///	user provided no target; code 4
+pub fn missing_target() {
+	println!("remux: no target provided");
+	exit(4);
+}
+
diff --git a/src/main.rs b/src/main.rs
index 66e5958..bbd9b49 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,8 +10,6 @@ fn main() {
 
 	let subcommand = args.subcommand().unwrap();
 
-	//let tmuxvar = var("TMUX");
-
 	match subcommand.as_deref() {
 		Some("h" | "help")
 			=>	command::help(&mut args),
diff --git a/src/util.rs b/src/util.rs
index 842e1b6..69fccbb 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -8,6 +8,7 @@ use tmux_interface::{
 	variables::session::session::SESSION_ALL
 };
 
+///	return a Vec of all sessions or None
 pub fn get_sessions() -> Option<Vec<Session>> {
 	let i_sessions = Sessions::get(SESSION_ALL);
 	if i_sessions.is_err() { return None; }
@@ -17,6 +18,7 @@ pub fn get_sessions() -> Option<Vec<Session>> {
 	Some(sessions.unwrap().0)
 }
 
+///	show the tmux nest text if env var is not unset
 pub fn prevent_nest() {
 	let tmux = var("TMUX").ok();
 	if tmux.is_some() && tmux.unwrap() != "" {