diff --git a/Cargo.lock b/Cargo.lock
index 8cbed05..2e606b1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -20,6 +20,12 @@ version = "1.0.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a20104e2335ce8a659d6dd92a51a767a0c062599c73b343fd152cb401e828c3d"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "clap"
 version = "4.1.1"
@@ -57,6 +63,26 @@ dependencies = [
  "os_str_bytes",
 ]
 
+[[package]]
+name = "directories"
+version = "4.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f51c5d4ddabd36886dd3e1438cb358cdcb0d7c499cb99cb4ac2e38e18b5cb210"
+dependencies = [
+ "dirs-sys",
+]
+
+[[package]]
+name = "dirs-sys"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b1d1d91c932ef41c0f2663aa8b0ca0342d444d842c06914aa0a7e352d0bada6"
+dependencies = [
+ "libc",
+ "redox_users",
+ "winapi",
+]
+
 [[package]]
 name = "errno"
 version = "0.2.8"
@@ -78,6 +104,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c05aeb6a22b8f62540c194aac980f2115af067bfe15a0734d7277a768d396b31"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.12.3"
@@ -203,6 +240,26 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb5a58c1855b4b6819d59012155603f0b22ad30cad752600aadfcb695265519a"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "redox_users"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b033d837a7cf162d7993aded9304e30a83213c648b6e389db233191f891e5c2b"
+dependencies = [
+ "getrandom",
+ "redox_syscall",
+ "thiserror",
+]
+
 [[package]]
 name = "rustix"
 version = "0.36.6"
@@ -278,6 +335,7 @@ name = "system-updater"
 version = "0.1.0"
 dependencies = [
  "clap",
+ "directories",
  "serde",
  "serde_yaml",
 ]
@@ -291,6 +349,26 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.38"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a9cd18aa97d5c45c6603caea1da6628790b37f7a34b6ca89522331c5180fed0"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.38"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fb327af4685e4d03fa8cbcf1716380da910eeb2bb8be417e7f9fd3fb164f36f"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.6"
@@ -309,6 +387,12 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/Cargo.toml b/Cargo.toml
index b1a7be5..c3a1924 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,5 +11,6 @@ name = "sup"
 
 [dependencies]
 clap = { version = "4.1", features = ["derive"] }
+directories = "4.0"
 serde = { version = "1.0", features = ["derive"] }
 serde_yaml = "0.9"
diff --git a/examples/apt.yaml b/examples/apt.yaml
new file mode 100644
index 0000000..9fc978f
--- /dev/null
+++ b/examples/apt.yaml
@@ -0,0 +1,25 @@
+packages:
+  - name: Apt
+    fetch:
+      exe: sudo
+      params:
+      - apt
+      - update
+      current_dir: null
+      env: {}
+    compile: null
+    install:
+      exe: sudo
+      params:
+      - apt
+      - upgrade
+      - --yes
+      current_dir: null
+      env: {}
+    post_install:
+      - exe: sudo
+        params:
+        - apt
+        - autoremove
+        current_dir: null
+        env: {}
diff --git a/examples/debian.yml b/examples/debian.yml
deleted file mode 100644
index ccd0404..0000000
--- a/examples/debian.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-systems:
-- name: Apt
-  fetch:
-    exe: sudo
-    params:
-    - apt
-    - update
-    current_dir: null
-    env: {}
-  compile: null
-  install:
-    exe: sudo
-    params:
-    - apt
-    - upgrade
-    - --yes
-    current_dir: null
-    env: {}
-  post_install:
-    - exe: sudo
-      params:
-      - apt
-      - autoremove
-      current_dir: null
-      env: {}
-- name: Rustup
-  install:
-    exe: rustup
-    params:
-    - update
-    current_dir: null
-    env: {}
-- name: Cargo
-  install:
-    exe: cargo
-    params:
-    - install-update
-    - -a
-    current_dir: null
-    env: {}
diff --git a/examples/flatpack.yaml b/examples/flatpack.yaml
new file mode 100644
index 0000000..be7af86
--- /dev/null
+++ b/examples/flatpack.yaml
@@ -0,0 +1,29 @@
+packages:
+  - name: Flatpack
+    fetch:
+      exe: flatpak
+      params:
+      - update
+      - --no-deploy
+      - --assumeyes
+      - --noninteractive
+      current_dir: null
+      env: {}
+    install:
+      exe: flatpak
+      params:
+      - update
+      - --no-pull
+      - --assumeyes
+      - --noninteractive
+      current_dir: null
+      env: {}
+    post-install:
+      - exe: flatpak
+        params:
+        - uninstall
+        - --unused
+        - --assumeyes
+        - --noninteractive
+        current_dir: null
+        env: {}
diff --git a/examples/openSUSE.yml b/examples/openSUSE.yml
deleted file mode 100644
index 74427c9..0000000
--- a/examples/openSUSE.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-systems:
-- fetch:
-    exe: sudo
-    params:
-    - zypper
-    - refresh
-    current_dir: null
-    env: {}
-  compile: null
-  install:
-    exe: sudo
-    params:
-    - zypper
-    - dup
-    current_dir: null
-    env: {}
-- install:
-    exe: rustup
-    params:
-    - update
-    current_dir: null
-    env: {}
-- install:
-    exe: cargo
-    params:
-    - install-update
-    - -a
-    current_dir: null
-    env: {}
diff --git a/examples/pipx.yaml b/examples/pipx.yaml
new file mode 100644
index 0000000..60c2d52
--- /dev/null
+++ b/examples/pipx.yaml
@@ -0,0 +1,8 @@
+packages:
+  - name: Pipx
+    install:
+      exe: pipx
+      params:
+      - upgrade-all
+      current_dir: null
+      env: {}
diff --git a/examples/rust.yaml b/examples/rust.yaml
new file mode 100644
index 0000000..4a774b2
--- /dev/null
+++ b/examples/rust.yaml
@@ -0,0 +1,16 @@
+packages:
+  - name: Rustup
+    install:
+      exe: rustup
+      params:
+      - update
+      current_dir: null
+      env: {}
+  - name: Cargo
+    install:
+      exe: cargo
+      params:
+      - install-update
+      - -a
+      current_dir: null
+      env: {}
diff --git a/src/command.rs b/src/command.rs
index 486b1eb..eccb64f 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -4,7 +4,7 @@ use std::collections::HashMap;
 use std::io::{stdout, Write};
 use std::path::PathBuf;
 use std::process::{Command, ExitStatus, Stdio};
-use std::{fmt, io};
+use std::{fmt, fs, io};
 
 #[derive(Debug, Serialize, Deserialize, PartialEq)]
 enum UpdateSteps {
@@ -16,11 +16,17 @@ enum UpdateSteps {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct Updater {
-    systems: Vec<System>,
+    pub systems: Vec<System>,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct System {
+    packages: Vec<Package>,
+    // TODO: => make a system dependend on another? This will allow to give a "Rust" config which update "rustup", and a custom "git helix" could then be executed after (with the updated toolchain, and NOT concurrently)
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Package {
     pub name: String,
     fetch: Option<Cmd>,
     compile: Option<Cmd>,
@@ -74,54 +80,120 @@ impl From<&String> for UpdateSteps {
     }
 }
 
+pub fn get_packages_folder(opt: &Opt) -> io::Result<PathBuf> {
+    let config_folder = directories::ProjectDirs::from("net", "ZykiCorp", "System Updater")
+        .ok_or(io::Error::new(
+            io::ErrorKind::NotFound,
+            "System’s configuration folder: for its standard location see https://docs.rs/directories/latest/directories/struct.ProjectDirs.html#method.config_dir",
+        ))?
+        .config_dir()
+        .join("packages");
+
+    Ok(config_folder)
+}
+
 impl Updater {
     fn new() -> Updater {
-        let mut up = Updater { systems: vec![] };
-        up.systems.push(System {
-            name: Default::default(),
-            fetch: None,
-            compile: None,
-            install: Cmd::new(),
-            post_install: None,
-        });
-        up
+        Updater { systems: vec![] }
     }
 
-    /// To create a sample config from code
+    // /// To create a sample config from code
     #[doc(hidden)]
     fn write_config(&self, opt: &Opt) {
         use std::fs::OpenOptions;
 
+        let config_folder = get_packages_folder(&opt).unwrap();
+
         let mut f = OpenOptions::new()
             .write(true)
             .create(true)
             .truncate(true)
-            .open(&opt.config_file)
+            .open(config_folder.join("default.yaml"))
             .unwrap();
 
+        fs::create_dir_all(&config_folder).unwrap();
+
         f.write_all(serde_yaml::to_string(&self).unwrap().as_bytes())
             .unwrap();
     }
 
-    pub fn from_config(opt: &Opt) -> Result<Updater> {
-        // let u = Updater::new();
-        // u.write_config(opt);
+    // TODO: add option to use &opt.config_file (or folder?) instead
+    pub fn from_config(opt: &Opt) -> io::Result<Updater> {
+        let mut updater = Updater::new();
 
-        let file = std::fs::read_to_string(&opt.config_file).unwrap();
-        Ok(serde_yaml::from_str(&file).unwrap())
+        if false {
+            updater.systems.push(System { packages: vec![] });
+            updater.systems[0].packages.push(Package {
+                name: "apt".to_owned(),
+                fetch: None,
+                compile: None,
+                install: Cmd {
+                    exe: "()".to_owned(),
+                    params: vec![],
+                    current_dir: None,
+                    env: HashMap::new(),
+                },
+                post_install: None,
+            });
+
+            updater.systems[0].packages.push(Package {
+                name: "Rustup".to_owned(),
+                fetch: None,
+                compile: None,
+                install: Cmd {
+                    exe: "rustup".to_owned(),
+                    params: vec!["self".to_owned(), "update".to_owned()],
+                    current_dir: None,
+                    env: HashMap::new(),
+                },
+                post_install: None,
+            });
+            updater.write_config(opt);
+
+            panic!("Wrote a config sample.");
+        }
+
+        let packages_folder = get_packages_folder(&opt)?;
+        match packages_folder.try_exists() {
+            Ok(true) => {} // Ok: Exist and should be readable
+            Ok(false) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::Other,
+                    format!(
+                        "Configuration folder not accessible at: {}. (broken symlink?)",
+                        packages_folder.display()
+                    ),
+                ))
+            }
+            Err(e) => return Err(e),
+        }
+
+        for file in packages_folder.read_dir()? {
+            let file = packages_folder.join(file?.path()); // "default.yaml");
+            let sys = std::fs::read_to_string(&file).unwrap();
+            let toto = serde_yaml::from_str(&sys).unwrap();
+            updater.systems.push(toto);
+        }
+
+        eprintln!("{:#?}", updater);
+
+        Ok(updater)
     }
 
     pub fn update_all(&self, opt: &Opt) -> Summary {
-        // self.systems.iter().collect();
         let mut status: Vec<_> = vec![];
+
+        // XXX: We may parallelise (iter_par from rayon?) this loop. But the UI will be problematic to handle
         for sys in &self.systems {
-            status.push((sys.name.clone(), self.update(&sys, opt).into()));
+            for pkg in &sys.packages {
+                status.push((pkg.name.clone(), self.update(&pkg, opt).into()));
+            }
         }
 
         Summary { status }
     }
 
-    fn update(&self, sys: &System, opt: &Opt) -> Result<()> {
+    fn update(&self, sys: &Package, opt: &Opt) -> Result<()> {
         // TODO: compute once before calling this function, maybe?
         let steps = if opt.steps.is_empty() {
             vec![
@@ -151,7 +223,7 @@ impl Updater {
     }
 }
 
-impl System {
+impl Package {
     pub fn fetch(&self, opt: &Opt) -> Result<()> {
         if let Some(fetch) = &self.fetch {
             let cmd = fetch.clone().prepare(opt);
diff --git a/src/lib.rs b/src/lib.rs
index 2910cb6..fb03103 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,25 +1,18 @@
 mod command;
-mod errors;
+pub mod errors;
 
 use command::*;
 use errors::*;
 
 use clap::Parser;
 use std::fmt::Display;
+use std::io;
 use std::path::PathBuf;
 
 #[derive(Parser)]
 pub struct Opt {
-    // TODO: transform this to "base" folder?
-    // XXX: use the directory/directory-next crate to get the "~/.config/sup" folder?
-    //     ++   A config subFolder and execute in alphabetical order?
-    //     +    One config file? -> confy crate?
-    //     -    A master config file that list the sub/real files? no if it mean parsing 2 differents formats
-    //
-    // Default to something like -> "~/.config/system-updater/list.yml".into(),
-    //
-    //#[arg(default_value_t = PathBuf::from("examples/debian.yml"))]
-    pub config_file: PathBuf,
+    #[arg(hide = true)] // TODO: hidden option for debug? or usefull for everyone?
+    pub config_file: Option<PathBuf>,
 
     #[arg(short, long)]
     pub quiet: bool, // TODO: use clap_verbosity_flag instead
@@ -72,8 +65,19 @@ impl Display for Summary {
     }
 }
 
-pub fn run(opt: &Opt) -> Summary {
-    let updater = Updater::from_config(opt).unwrap();
+pub fn run(opt: &Opt) -> io::Result<Summary> {
+    let updater = Updater::from_config(opt)?;
 
-    updater.update_all(opt)
+    if updater.systems.is_empty() {
+        let package_folder = get_packages_folder(&opt)?;
+        return Err(io::Error::new(
+            io::ErrorKind::Other,
+            format!(
+                "No package found in configuration folder. Add them in: {}",
+                package_folder.display()
+            ),
+        ));
+    }
+
+    Ok(updater.update_all(opt))
 }
diff --git a/src/main.rs b/src/main.rs
index 3222b1a..8d66e08 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,10 +1,12 @@
-use clap::Parser;
 use system_updater::*;
 
-fn main() {
+use clap::Parser;
+
+fn main() -> std::io::Result<()> {
     let opt = Opt::parse();
 
-    let summary = run(&opt);
+    let summary = run(&opt)?;
 
     println!("{}", summary);
+    Ok(())
 }