diff --git a/src/command/builtin.rs b/src/command/builtins.rs
similarity index 52%
rename from src/command/builtin.rs
rename to src/command/builtins.rs
index d0d3db3..8201c9e 100644
--- a/src/command/builtin.rs
+++ b/src/command/builtins.rs
@@ -1,15 +1,9 @@
-use super::Command;
 use crate::{error::print_error, exit_code::ExitCode};
 
 use std::env;
 use std::{env::set_current_dir, path::PathBuf};
 
-type BuiltinFunction = fn(&Vec<String>) -> ExitCode;
-
-#[derive(Debug)]
-pub struct NoSuchBuiltinError;
-
-fn cd(args: &Vec<String>) -> ExitCode {
+pub fn cd(args: &Vec<String>) -> ExitCode {
     let path: Option<PathBuf>;
 
     if !args.is_empty() {
@@ -37,27 +31,3 @@ fn cd(args: &Vec<String>) -> ExitCode {
 
     exit_code
 }
-
-pub struct Builtin {
-    function: BuiltinFunction,
-    args: Vec<String>,
-}
-
-impl Builtin {
-    pub fn new(argv: &Vec<String>) -> Result<Self, NoSuchBuiltinError> {
-        let mut args = argv.clone();
-        let program = args.remove(0);
-
-        if program == "cd" {
-            Ok(Self { function: cd, args })
-        } else {
-            Err(NoSuchBuiltinError)
-        }
-    }
-}
-
-impl Command for Builtin {
-    fn spawn(&mut self) -> ExitCode {
-        (self.function)(&self.args)
-    }
-}
diff --git a/src/command/command_builder.rs b/src/command/command_builder.rs
index 69a476c..9c523a7 100644
--- a/src/command/command_builder.rs
+++ b/src/command/command_builder.rs
@@ -1,6 +1,6 @@
-use super::builtin::Builtin;
-use super::unix_program::UnixProgram;
+use super::Builtin;
 use super::Command;
+use super::UnixProgram;
 
 pub struct CommandBuilder {
     argv: Vec<String>,
diff --git a/src/command/command_sequence.rs b/src/command/command_sequence.rs
index ee7a09e..4918d76 100644
--- a/src/command/command_sequence.rs
+++ b/src/command/command_sequence.rs
@@ -2,22 +2,27 @@ use crate::command::Command;
 use crate::exit_code::ExitCode;
 
 pub struct CommandSequence {
-    command: Box<dyn Command>,
+    command: Option<Box<dyn Command>>,
     next_command: Option<Box<CommandSequence>>,
 }
 
 impl CommandSequence {
-    pub fn new(command: Box<dyn Command>) -> Self {
+    pub fn new() -> Self {
         Self {
-            command,
+            command: None,
             next_command: None,
         }
     }
 
-    #[allow(dead_code)]
     pub fn add(&mut self, command: Box<dyn Command>) {
-        if self.next_command.is_none() {
-            self.next_command = Some(Box::new(Self::new(command)));
+        if self.command.is_none() {
+            self.command = Some(command);
+        } else if self.next_command.is_none() {
+            let new_command = Self {
+                command: Some(command),
+                next_command: None,
+            };
+            self.next_command = Some(Box::new(new_command));
         } else {
             self.next_command.as_mut().unwrap().add(command);
         }
@@ -26,10 +31,14 @@ impl CommandSequence {
 
 impl Command for CommandSequence {
     fn spawn(&mut self) -> ExitCode {
-        let mut exit_code = self.command.spawn();
+        let mut exit_code = ExitCode::success();
 
-        if self.next_command.is_some() {
-            exit_code = self.next_command.as_mut().unwrap().spawn();
+        if self.command.is_some() {
+            exit_code = self.command.as_mut().unwrap().spawn();
+
+            if self.next_command.is_some() {
+                exit_code = self.next_command.as_mut().unwrap().spawn();
+            }
         }
 
         exit_code
diff --git a/src/command/mod.rs b/src/command/mod.rs
index da38895..07fa206 100644
--- a/src/command/mod.rs
+++ b/src/command/mod.rs
@@ -1,10 +1,94 @@
-pub mod builtin;
+mod builtins;
 pub mod command_builder;
 pub mod command_sequence;
-pub mod unix_program;
 
+use crate::error::print_error;
 use crate::exit_code::ExitCode;
 
+type BuiltinFunction = fn(&Vec<String>) -> ExitCode;
+
+#[derive(Debug)]
+pub struct NoSuchBuiltinError;
+
 pub trait Command {
     fn spawn(&mut self) -> ExitCode;
 }
+
+pub struct Builtin {
+    function: BuiltinFunction,
+    args: Vec<String>,
+}
+
+impl Builtin {
+    pub fn new(argv: &Vec<String>) -> Result<Self, NoSuchBuiltinError> {
+        let mut args = argv.clone();
+        let program = args.remove(0);
+
+        if program == "cd" {
+            Ok(Self {
+                function: builtins::cd,
+                args,
+            })
+        } else {
+            Err(NoSuchBuiltinError)
+        }
+    }
+}
+
+impl Command for Builtin {
+    fn spawn(&mut self) -> ExitCode {
+        (self.function)(&self.args)
+    }
+}
+
+pub struct UnixProgram {
+    command: std::process::Command,
+}
+
+impl UnixProgram {
+    pub fn new(argv: &Vec<String>) -> Self {
+        let mut argv = argv.clone();
+        let program = argv.remove(0);
+        let mut command = std::process::Command::new(&program);
+        command.args(argv);
+
+        Self { command }
+    }
+}
+
+impl Command for UnixProgram {
+    fn spawn(&mut self) -> ExitCode {
+        let handle = self.command.spawn();
+
+        if handle.is_ok() {
+            let exit_code = handle
+                .unwrap()
+                .wait()
+                .expect("error waiting for the child")
+                .code()
+                .unwrap_or(1);
+
+            let exit_code = match u8::try_from(exit_code) {
+                Ok(code) => ExitCode::new(code),
+                Err(_e) => ExitCode::new(u8::MAX),
+            };
+
+            exit_code
+        } else {
+            let message = format!(
+                "{}: command not found",
+                self.command.get_program().to_str().unwrap()
+            );
+            print_error(message.as_str());
+            ExitCode::not_found()
+        }
+    }
+}
+
+struct Nothing;
+
+impl Command for Nothing {
+    fn spawn(&mut self) -> ExitCode {
+        ExitCode::success()
+    }
+}
diff --git a/src/command/unix_program.rs b/src/command/unix_program.rs
deleted file mode 100644
index a7df9c5..0000000
--- a/src/command/unix_program.rs
+++ /dev/null
@@ -1,47 +0,0 @@
-use crate::command::Command;
-use crate::error::print_error;
-use crate::exit_code::ExitCode;
-
-pub struct UnixProgram {
-    command: std::process::Command,
-}
-
-impl UnixProgram {
-    pub fn new(argv: &Vec<String>) -> Self {
-        let mut argv = argv.clone();
-        let program = argv.remove(0);
-        let mut command = std::process::Command::new(&program);
-        command.args(argv);
-
-        Self { command }
-    }
-}
-
-impl Command for UnixProgram {
-    fn spawn(&mut self) -> ExitCode {
-        let handle = self.command.spawn();
-
-        if handle.is_ok() {
-            let exit_code = handle
-                .unwrap()
-                .wait()
-                .expect("error waiting for the child")
-                .code()
-                .unwrap_or(1);
-
-            let exit_code = match u8::try_from(exit_code) {
-                Ok(code) => ExitCode::new(code),
-                Err(_e) => ExitCode::new(u8::MAX),
-            };
-
-            exit_code
-        } else {
-            let message = format!(
-                "{}: command not found",
-                self.command.get_program().to_str().unwrap()
-            );
-            print_error(message.as_str());
-            ExitCode::not_found()
-        }
-    }
-}
diff --git a/src/control.rs b/src/control.rs
index 86c0a2e..5695a78 100644
--- a/src/control.rs
+++ b/src/control.rs
@@ -1,7 +1,7 @@
 use crate::command::Command;
 use crate::exit_code::ExitCode;
 use crate::interface::{get_user_input, print_prompt};
-use crate::parser::parse_command_line;
+use crate::parser::parse;
 
 fn exit(code: &ExitCode) {
     let code = i32::from(code.get());
@@ -17,7 +17,7 @@ pub fn run() {
         let user_input = get_user_input();
 
         if user_input.is_some() {
-            let command_sequence = parse_command_line(user_input.unwrap());
+            let command_sequence = parse(user_input.unwrap());
 
             if command_sequence.is_some() {
                 current_exit_code = command_sequence.unwrap().spawn();
diff --git a/src/parser.rs b/src/parser.rs
index 057499e..cb9207e 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -17,7 +17,7 @@ fn parse_quote(characters: &mut Vec<char>) -> Result<String, UnmatchedQuoteError
     }
 }
 
-fn build_argv(characters: &mut Vec<char>, current_arg: &mut String) -> Vec<String> {
+fn parse_main(characters: &mut Vec<char>, current_arg: &mut String) -> Vec<String> {
     if characters.is_empty() {
         vec![]
     } else {
@@ -26,34 +26,40 @@ fn build_argv(characters: &mut Vec<char>, current_arg: &mut String) -> Vec<Strin
         if current_char.is_whitespace() {
             if !current_arg.is_empty() {
                 let mut argv: Vec<String> = vec![current_arg.clone()];
-                argv.append(&mut build_argv(characters, &mut String::from("")));
+                argv.append(&mut parse_main(characters, &mut String::from("")));
 
                 argv
             } else {
-                build_argv(characters, current_arg)
+                parse_main(characters, current_arg)
             }
         } else if current_char == '\'' {
             let mut argv = vec![parse_quote(characters).unwrap()];
-            argv.append(&mut build_argv(characters, &mut String::default()));
+            argv.append(&mut parse_main(characters, &mut String::default()));
 
             argv
         } else {
             current_arg.push(current_char);
-            build_argv(characters, current_arg)
+            parse_main(characters, current_arg)
         }
     }
 }
 
-pub fn parse_command_line(line: String) -> Option<CommandSequence> {
+pub fn parse(line: String) -> Option<CommandSequence> {
     let mut characters: Vec<char> = line.chars().rev().collect();
-    let argv = build_argv(&mut characters, &mut String::default());
+
+    None
+    /*
+    let argv = parse_main(&mut characters, &mut String::default());
 
     if !argv.is_empty() {
         let command = CommandBuilder::new(argv).build();
-        Some(CommandSequence::new(command))
+        let mut command_sequence = CommandSequence::new();
+        command_sequence.add(command);
+        Some(command_sequence)
     } else {
         None
     }
+    */
 }
 
 #[derive(Debug)]