diff --git a/src/cmd.rs b/src/cmd.rs
new file mode 100644
index 0000000..910c3fc
--- /dev/null
+++ b/src/cmd.rs
@@ -0,0 +1,24 @@
+use std::os::unix::process::CommandExt;
+use std::path::Path;
+use std::process::Command;
+
+use crate::Package;
+
+pub fn run_edit_command(files: &[&Path]) {
+    let mut cmd = Command::new("nvim");
+    for f in files {
+        cmd.arg(f.to_string_lossy().to_string());
+    }
+    dbg!(&cmd);
+    cmd.exec();
+}
+
+pub fn run_install_command(diff: Vec<Package>) {
+    let mut cmd = Command::new("paru");
+    cmd.arg("-S");
+    for p in diff {
+        cmd.arg(format!("{p}"));
+    }
+    dbg!(&cmd);
+    cmd.exec();
+}
diff --git a/src/core.rs b/src/core.rs
new file mode 100644
index 0000000..70d271b
--- /dev/null
+++ b/src/core.rs
@@ -0,0 +1,121 @@
+use std::collections::HashSet;
+use std::path::PathBuf;
+use std::process::exit;
+
+use crate::args;
+use crate::cmd::run_install_command;
+use crate::db::{get_all_installed_packages, get_explicitly_installed_packages};
+use crate::group::{Group, GROUPS_DIR};
+use crate::package::Package;
+
+use clap::ArgMatches;
+
+pub struct Pacdef {
+    pub(crate) args: ArgMatches,
+    pub(crate) groups: Option<HashSet<Group>>,
+    // action: Box<dyn Fn(Self)>,
+}
+
+impl Pacdef {
+    pub fn new(args: ArgMatches, groups: HashSet<Group>) -> Self {
+        Self {
+            args,
+            groups: Some(groups),
+            // action: Box::new(Self::install_packages),
+        }
+    }
+
+    pub(crate) fn take_packages_as_set(&mut self) -> HashSet<Package> {
+        self.groups
+            .take()
+            .unwrap()
+            .into_iter()
+            .flat_map(|g| g.packages)
+            .collect()
+    }
+
+    pub(crate) fn get_packages_to_install(&mut self) -> Vec<Package> {
+        let managed = self.take_packages_as_set();
+        let local_packages = get_all_installed_packages();
+        let mut diff: Vec<_> = managed
+            .into_iter()
+            .filter(|p| !local_packages.contains(p))
+            .collect();
+        diff.sort_unstable();
+        diff
+    }
+
+    pub(crate) fn install_packages(mut self) {
+        let diff = self.get_packages_to_install();
+        if diff.is_empty() {
+            println!("nothing to do");
+            exit(0);
+        }
+        println!("Would install the following packages:");
+        for p in &diff {
+            println!("  {p}");
+        }
+        println!();
+        crate::ui::get_user_confirmation();
+
+        run_install_command(diff);
+    }
+
+    pub fn run_action_from_arg(self) {
+        match self.args.subcommand() {
+            // Some((args::EDIT, groups)) => println!("{groups:#?}"),
+            Some((args::EDIT, groups)) => self.edit_group_files(groups),
+            Some((args::GROUPS, _)) => self.show_groups(),
+            Some((args::SYNC, _)) => self.install_packages(),
+            Some((args::UNMANAGED, _)) => self.show_unmanaged_packages(),
+            Some((args::VERSION, _)) => self.show_version(),
+            _ => todo!(),
+        }
+    }
+
+    pub(crate) fn edit_group_files(&self, groups: &ArgMatches) {
+        let files: Vec<_> = groups
+            .get_many::<String>("group")
+            .unwrap()
+            .map(|file| {
+                let mut buf = PathBuf::from(GROUPS_DIR);
+                buf.push(file);
+                buf
+            })
+            .collect();
+        for f in files {
+            println!("{f:#?}");
+        }
+    }
+
+    pub(crate) fn show_version(self) {
+        println!("pacdef, version: {}", env!("CARGO_PKG_VERSION"))
+    }
+
+    pub(crate) fn show_unmanaged_packages(mut self) {
+        for p in &self.get_unmanaged_packages() {
+            println!("{p}");
+        }
+    }
+
+    /// Returns a `Vec` of alphabetically sorted unmanaged packages.
+    pub(crate) fn get_unmanaged_packages(&mut self) -> Vec<Package> {
+        let managed = self.take_packages_as_set();
+        let explicitly_installed = get_explicitly_installed_packages();
+        let mut result: Vec<_> = explicitly_installed
+            .into_iter()
+            .filter(|p| !managed.contains(p))
+            .collect();
+        result.sort_unstable();
+        result
+    }
+
+    pub(crate) fn show_groups(mut self) {
+        let groups = self.groups.take().unwrap();
+        let mut vec: Vec<_> = groups.iter().collect();
+        vec.sort_unstable();
+        for g in vec {
+            println!("{}", g.name);
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 3a0e40f..34189cb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,6 @@
 pub mod args;
+mod cmd;
+pub mod core;
 pub mod db;
 pub mod group;
 pub mod package;
diff --git a/src/main.rs b/src/main.rs
index 280653d..8253805 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,150 +1,12 @@
-use std::os::unix::process::CommandExt;
-use std::path::{Path, PathBuf};
-use std::process::exit;
-use std::{collections::HashSet, process::Command};
-
 use anyhow::Result;
-use clap::ArgMatches;
 
 use pacdef::args;
-use pacdef::db::{get_all_installed_packages, get_explicitly_installed_packages};
-use pacdef::group::GROUPS_DIR;
 use pacdef::Group;
-use pacdef::Package;
 
 fn main() -> Result<()> {
     let args = args::get_matched_arguments();
     let groups = Group::load_from_dir();
-    let pacdef = Pacdef::new(args, groups);
+    let pacdef = pacdef::core::Pacdef::new(args, groups);
     pacdef.run_action_from_arg();
     Ok(())
 }
-
-fn run_edit_command(files: &[&Path]) {
-    let mut cmd = Command::new("nvim");
-    for f in files {
-        cmd.arg(f.to_string_lossy().to_string());
-    }
-    dbg!(&cmd);
-    cmd.exec();
-}
-
-fn run_install_command(diff: Vec<Package>) {
-    let mut cmd = Command::new("paru");
-    cmd.arg("-S");
-    for p in diff {
-        cmd.arg(format!("{p}"));
-    }
-    dbg!(&cmd);
-    cmd.exec();
-}
-
-struct Pacdef {
-    args: ArgMatches,
-    groups: Option<HashSet<Group>>,
-    // action: Box<dyn Fn(Self)>,
-}
-
-impl Pacdef {
-    fn new(args: ArgMatches, groups: HashSet<Group>) -> Self {
-        Self {
-            args,
-            groups: Some(groups),
-            // action: Box::new(Self::install_packages),
-        }
-    }
-
-    fn take_packages_as_set(&mut self) -> HashSet<Package> {
-        self.groups
-            .take()
-            .unwrap()
-            .into_iter()
-            .flat_map(|g| g.packages)
-            .collect()
-    }
-
-    fn get_packages_to_install(&mut self) -> Vec<Package> {
-        let managed = self.take_packages_as_set();
-        let local_packages = get_all_installed_packages();
-        let mut diff: Vec<_> = managed
-            .into_iter()
-            .filter(|p| !local_packages.contains(p))
-            .collect();
-        diff.sort_unstable();
-        diff
-    }
-
-    fn install_packages(mut self) {
-        let diff = self.get_packages_to_install();
-        if diff.is_empty() {
-            println!("nothing to do");
-            exit(0);
-        }
-        println!("Would install the following packages:");
-        for p in &diff {
-            println!("  {p}");
-        }
-        println!();
-        pacdef::ui::get_user_confirmation();
-
-        run_install_command(diff);
-    }
-
-    fn run_action_from_arg(self) {
-        match self.args.subcommand() {
-            // Some((args::EDIT, groups)) => println!("{groups:#?}"),
-            Some((args::EDIT, groups)) => self.edit_group_files(groups),
-            Some((args::GROUPS, _)) => self.show_groups(),
-            Some((args::SYNC, _)) => self.install_packages(),
-            Some((args::UNMANAGED, _)) => self.show_unmanaged_packages(),
-            Some((args::VERSION, _)) => self.show_version(),
-            _ => todo!(),
-        }
-    }
-
-    fn edit_group_files(&self, groups: &ArgMatches) {
-        let files: Vec<_> = groups
-            .get_many::<String>("group")
-            .unwrap()
-            .map(|file| {
-                let mut buf = PathBuf::from(GROUPS_DIR);
-                buf.push(file);
-                buf
-            })
-            .collect();
-        for f in files {
-            println!("{f:#?}");
-        }
-    }
-
-    fn show_version(self) {
-        println!("pacdef, version: {}", env!("CARGO_PKG_VERSION"))
-    }
-
-    fn show_unmanaged_packages(mut self) {
-        for p in &self.get_unmanaged_packages() {
-            println!("{p}");
-        }
-    }
-
-    /// Returns a `Vec` of alphabetically sorted unmanaged packages.
-    fn get_unmanaged_packages(&mut self) -> Vec<Package> {
-        let managed = self.take_packages_as_set();
-        let explicitly_installed = get_explicitly_installed_packages();
-        let mut result: Vec<_> = explicitly_installed
-            .into_iter()
-            .filter(|p| !managed.contains(p))
-            .collect();
-        result.sort_unstable();
-        result
-    }
-
-    fn show_groups(mut self) {
-        let groups = self.groups.take().unwrap();
-        let mut vec: Vec<_> = groups.iter().collect();
-        vec.sort_unstable();
-        for g in vec {
-            println!("{}", g.name);
-        }
-    }
-}
diff --git a/src/ui.rs b/src/ui.rs
index d3f98d7..3ea626e 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -1,9 +1,6 @@
+use std::io::{BufRead, Write};
 use std::process::exit;
 
-use std::io::Write::std::io;
-
-use std;
-
 pub(crate) fn get_user_confirmation() {
     print!("Continue? [Y/n] ");
     std::io::stdout().flush().unwrap();