Catch UnknownSSHError and do not use return codes

The runners were still checking for the return codes of
create_ssh_master_connection instead of catching the exception.
We now catch the exceptions we calling the runners in main.

.gitignore

@@ -1,2 +1,4 @@
 poetry.lock
 __pycache__
+docs/build
+dist/

README.md

@@ -23,5 +23,4 @@ The issue is that you need to know what data is stored on the server to avoid co
 # Developement
 
 Unisync was at first a simple bash script but as it grew more complex I started struggling to maintain it which is why I am porting it to python. It will make everything more robust, easier to maintain and to add functionalities.  
-I am in the early stages of the developement process, this should be usable in the upcoming weeks.  
-Help will be welcome in the future but is not desirable right now as I want to shape this the way I want to.
+I am in the early stages of the developement process, this should be usable someday (hopefully).  

docs/Makefile

@@ -0,0 +1,20 @@
+# Minimal makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line, and also
+# from the environment for the first two.
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+SOURCEDIR     = source
+BUILDDIR      = build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+.PHONY: help Makefile
+
+# Catch-all target: route all unknown targets to Sphinx using the new
+# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
+%: Makefile
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

docs/make.bat

@@ -0,0 +1,35 @@
+@ECHO OFF
+
+pushd %~dp0
+
+REM Command file for Sphinx documentation
+
+if "%SPHINXBUILD%" == "" (
+	set SPHINXBUILD=sphinx-build
+)
+set SOURCEDIR=source
+set BUILDDIR=build
+
+%SPHINXBUILD% >NUL 2>NUL
+if errorlevel 9009 (
+	echo.
+	echo.The 'sphinx-build' command was not found. Make sure you have Sphinx
+	echo.installed, then set the SPHINXBUILD environment variable to point
+	echo.to the full path of the 'sphinx-build' executable. Alternatively you
+	echo.may add the Sphinx directory to PATH.
+	echo.
+	echo.If you don't have Sphinx installed, grab it from
+	echo.https://www.sphinx-doc.org/
+	exit /b 1
+)
+
+if "%1" == "" goto help
+
+%SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+goto end
+
+:help
+%SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+
+:end
+popd

docs/source/conf.py

@@ -0,0 +1,36 @@
+# Configuration file for the Sphinx documentation builder.
+#
+# For the full list of built-in configuration values, see the documentation:
+# https://www.sphinx-doc.org/en/master/usage/configuration.html
+
+# -- Project information -----------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
+
+project = 'unisync'
+copyright = '2026, Paul Retourné'
+author = 'Paul Retourné'
+release = '0.1.0'
+
+# -- General configuration ---------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
+
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.viewcode',
+    'sphinx.ext.napoleon',
+    'sphinx.ext.todo'
+        ]
+
+templates_path = ['_templates']
+exclude_patterns = []
+
+
+
+# -- Options for HTML output -------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
+
+#html_theme = 'alabaster'
+html_theme = 'sphinx_rtd_theme'
+html_static_path = ['_static']
+
+autodoc_docstring_signature = True

docs/source/example.rst

@@ -0,0 +1,24 @@
+.. _example_how_it_works:
+
+Example of how unisync works
+============================
+
+Let's say you have the following structure::
+
+        $ tree .
+        .
+        ├── big_file
+        └── folder
+            ├── file
+            └── other_file
+
+If you only want to synchronise `folder` and its content on your laptop the following will be automatically generated::
+
+        $ tree .
+        .
+        ├── big_file -> ../.data/big_file
+        └── folder
+            ├── file
+            └── other_file
+
+`big_file` is now a symbolic link and by mounting the remote directory you can still seemlessly access `big_file` through the network.

docs/source/index.rst

@@ -0,0 +1,31 @@
+.. unisync documentation master file, created by
+   sphinx-quickstart on Sun Jan  4 15:02:58 2026.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+Documentation for unisync
+=========================
+
+Unisync is a data synchronising tool built around `unison`_ and expending on it.
+
+Unisync tries to solve two problems that are often solved separately but never together :
+
+* Keeping your data synchronised between multiple machines (through a central server), examples of this are rsync and of course unison.
+* Being able to access and edit files stored on your server without having to download them, the gui interface of nextcloud for example.
+* And of course I want to be able to do all of this without ever having to leave my terminal.
+
+Unisync solves this problem by placing each file on your local machine but with only the selected files and folders being physically present on your drive,
+the others are replaced by symbolic links pointing to a directory that is mounted from your server.
+
+See this
+:ref:`example_how_it_works`.
+
+.. _unison: https://github.com/bcpierce00/unison
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents:
+
+   example
+   modules
+

docs/source/modules.rst

@@ -0,0 +1,7 @@
+unisync
+=======
+
+.. toctree::
+   :maxdepth: 4
+
+   unisync

docs/source/unisync.rst

@@ -0,0 +1,77 @@
+unisync package
+===============
+
+Submodules
+----------
+
+unisync.argparser module
+------------------------
+
+.. automodule:: unisync.argparser
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.config module
+---------------------
+
+.. automodule:: unisync.config
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.defaults module
+-----------------------
+
+.. automodule:: unisync.defaults
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.errors module
+---------------------
+
+.. automodule:: unisync.errors
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.main module
+-------------------
+
+.. automodule:: unisync.main
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.paths module
+--------------------
+
+.. automodule:: unisync.paths
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.runners module
+----------------------
+
+.. automodule:: unisync.runners
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+unisync.synchroniser module
+---------------------------
+
+.. automodule:: unisync.synchroniser
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+Module contents
+---------------
+
+.. automodule:: unisync
+   :members:
+   :show-inheritance:
+   :undoc-members:

pyproject.toml

@@ -10,6 +10,9 @@ requires-python = ">=3.13"
 dependencies = [
 ]
 
+[project.scripts]
+unisync = "unisync.main:main"
+
 [tool.poetry]
 packages = [{include = "unisync", from = "src"}]
 
@@ -17,3 +20,12 @@ packages = [{include = "unisync", from = "src"}]
 [build-system]
 requires = ["poetry-core>=2.0.0,<3.0.0"]
 build-backend = "poetry.core.masonry.api"
+
+[dependency-groups]
+docs = [
+    "sphinx (>=9.1.0,<10.0.0)",
+    "sphinx-rtd-theme (>=3.0.2,<4.0.0)",
+]
+dev = [
+    "pylint (>=4.0.4,<5.0.0)"
+]

src/unisync/argparser.py

@@ -1,22 +1,36 @@
-# Copyright (C) 2025 Paul Retourné
+# Copyright (C) 2025-2026 Paul Retourné
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 import argparse
 
-def create_argparser() -> argparse.ArgumentParser:
+def create_argparser(sync_function, add_function, mount_function) -> argparse.ArgumentParser:
+    """
+    Creates an argument parser to parse the command line arguments.
+    We use subparsers and set a default function for each to perform the correct action.
+    """
     parser = argparse.ArgumentParser(
             prog='unisync',
             description='File synchronisation application',
-            epilog="""
-            Copyright © 2025 Paul Retourné.
-            License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>."""
+            epilog="Copyright © 2025-2026 Paul Retourné.\n"
+            "License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.",
+            formatter_class=argparse.RawDescriptionHelpFormatter
             )
     parser.add_argument("local", nargs="?")
     parser.add_argument("remote", nargs="?")
+    parser.set_defaults(func=sync_function)
 
     remote_addr_group = parser.add_mutually_exclusive_group()
     remote_addr_group.add_argument("--ip")
     remote_addr_group.add_argument("--hostname")
 
     parser.add_argument("--config", help="Path to the configuration file", metavar="path_to_config")
+
+    subparsers = parser.add_subparsers(help='Actions other than synchronisation')
+
+    parser_add = subparsers.add_parser('add', help='Add files to be synchronised.')
+    parser_add.set_defaults(func=add_function)
+
+    parser_mount = subparsers.add_parser('mount', help='Mount the remote.')
+    parser_mount.set_defaults(func=mount_function)
+
     return parser

src/unisync/config.py

@@ -1,22 +1,24 @@
-# Copyright (C) 2025 Paul Retourné
+# Copyright (C) 2025-2026 Paul Retourné
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 from configparser import UNNAMED_SECTION
-from dataclasses import dataclass, field
+from dataclasses import dataclass
 from pathlib import Path
 import ipaddress
 import configparser
 
+from unisync.defaults import *
+
 @dataclass
 class ServerConfig:
     """
     Dataclass keeping the config for connecting to the server
     """
     user: str
-    sshargs: str = ""
-    hostname: str = ""
-    ip: str = ""
-    port: int | None = 22
+    sshargs: str
+    hostname: str
+    ip: str
+    port: int
 
     def __post_init__(self):
         """
@@ -28,8 +30,8 @@ class ServerConfig:
         if self.ip != "":
             try:
                 ipaddress.ip_address(self.ip)
-            except ValueError:
-                raise ValueError("The provided ip address is invalid")
+            except ValueError as e:
+                raise ValueError("The provided ip address is invalid") from e
 
 @dataclass
 class RootsConfig:
@@ -44,15 +46,27 @@ class UnisonConfig:
     """
     Dataclass keeping unison specific configurations
     """
-    bools: list = field(default_factory=list)
-    values: dict = field(default_factory=dict)
+    bools: list
+    values: dict
+
+@dataclass
+class BackupConfig:
+    """
+    Configuration options relative to backing up the files.
+    """
+    enabled: bool
+    selection: str
+    location: str
+    max_backups: int
+    backupsuffix: str
+    backupprefix: str
 
 @dataclass
 class OtherConfig:
     """
     Dataclass keeping miscellanous configuration options
     """
-    cache_dir_path: Path = Path("~/.unisync").expanduser()
+    cache_dir_path: Path
 
 @dataclass
 class Config:
@@ -62,7 +76,8 @@ class Config:
     server: ServerConfig
     roots: RootsConfig
     unison: UnisonConfig
-    other: OtherConfig = field(default_factory=OtherConfig)
+    backup: BackupConfig
+    other: OtherConfig
 
 
 def load_config(config_path:str) -> Config:
@@ -79,29 +94,42 @@ def load_config(config_path:str) -> Config:
     # Check if sections are provided
     server_section = "Server" if "Server" in config.sections() else UNNAMED_SECTION
     roots_section = "Roots" if "Roots" in config.sections() else UNNAMED_SECTION
+    backup_section = "Backup"
+    other_section = "Other" if "Other" in config.sections() else UNNAMED_SECTION
 
     server_config = ServerConfig(
             config.get(server_section, "user"),
-            config.get(server_section, "sshargs", fallback=""),
-            config.get(server_section, "hostname", fallback=""),
-            config.get(server_section, "ip", fallback=""),
-            config.getint(server_section, "port", fallback=None)
+            config.get(server_section, "sshargs", fallback=DEFAULT_SERVER_SSHARGS),
+            config.get(server_section, "hostname", fallback=DEFAULT_SERVER_HOSTNAME),
+            config.get(server_section, "ip", fallback=DEFAULT_SERVER_IP),
+            config.getint(server_section, "port", fallback=DEFAULT_SERVER_PORT)
         )
     roots_config = RootsConfig(
-            config.get(roots_section, "local"),
+            config.get(roots_section, "local", fallback=DEFAULT_ROOTS_LOCAL),
             config.get(roots_section, "remote")
         )
+    backup_config = BackupConfig(
+            config.getboolean(backup_section, "enabled", fallback=DEFAULT_BACKUP_ENABLED),
+            config.get(backup_section, "selection", fallback=DEFAULT_BACKUP_SELECTION),
+            config.get(backup_section, "loction", fallback=DEFAULT_BACKUP_LOC),
+            config.getint(backup_section, "max_backups", fallback=DEFAULT_BACKUP_MAX_BACKUPS),
+            config.get(backup_section, "backupsuffix", fallback=DEFAULT_BACKUP_BACKUPSUFFIX),
+            config.get(backup_section, "backupprefix", fallback=DEFAULT_BACKUP_BACKUPPREFIX)
+        )
+    other_config = OtherConfig(
+            Path(config.get(other_section, "cache_dir_path", fallback=DEFAULT_MISC_CACHE_DIR_PATH)).expanduser()
+        )
 
-    args_bool = list()
-    args_val = dict()
+    args_bool = []
+    args_val = {}
     if "Unison" in config.sections():
         for key, val in config.items("Unison"):
             if key in config["DEFAULT"].keys():
                 continue
-            elif val == "" or val == None:
+            if val in ("", None):
                 args_bool.append(key)
             else:
                 args_val[key] = val
     unison_config = UnisonConfig(args_bool, args_val)
 
-    return Config(server_config, roots_config, unison_config)
+    return Config(server_config, roots_config, unison_config, backup_config, other_config)

src/unisync/defaults.py

@@ -0,0 +1,25 @@
+# Copyright (c) 2026 paul retourné
+# spdx-license-identifier: gpl-3.0-or-later
+
+from pathlib import Path
+
+# Commented out values are part of the config but are required so there is no defaults.
+# This allows this file to be a list of all the config options.
+
+# DEFAULT_SERVER_USER: str = ""
+DEFAULT_SERVER_SSHARGS: str = ""
+DEFAULT_SERVER_HOSTNAME: str = ""
+DEFAULT_SERVER_IP: str = ""
+DEFAULT_SERVER_PORT: int = 22
+
+DEFAULT_ROOTS_LOCAL: str = str(Path("~/files").expanduser())
+# DEFAULT_ROOTS_REMOTE: str = ""
+
+DEFAULT_MISC_CACHE_DIR_PATH: str = "~/.unisync"
+
+DEFAULT_BACKUP_ENABLED: bool = False
+DEFAULT_BACKUP_SELECTION: str = ""
+DEFAULT_BACKUP_LOC: str = "local"
+DEFAULT_BACKUP_MAX_BACKUPS: int = 2
+DEFAULT_BACKUP_BACKUPSUFFIX: str = ".$VERSION.bak"
+DEFAULT_BACKUP_BACKUPPREFIX: str = ".unison_backups/"

src/unisync/errors.py

@@ -1,5 +1,21 @@
-class RemoteMountedError(BaseException):
+# Copyright (C) 2025-2026 Paul Retourné
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from typing import NoReturn
+import sys
+
+class RemoteMountedError(Exception):
     pass
 
-class InvalidMountError(BaseException):
+class InvalidMountError(Exception):
     pass
+
+class UnknownSSHError(Exception):
+    pass
+
+class FatalSyncError(Exception):
+    pass
+
+def unisync_exit_fatal(reason:str) -> NoReturn:
+    print(reason)
+    sys.exit(1)

src/unisync/main.py

@@ -1,25 +1,30 @@
-# Copyright (C) 2025 Paul Retourné
+# Copyright (C) 2025-2026 Paul Retourné
 # SPDX-License-Identifier: GPL-3.0-or-later
 
-import os
-from argparser import create_argparser
-from config import RootsConfig, ServerConfig, Config, load_config
-from synchroniser import Synchroniser
-from pathlib import Path, PosixPath
-from paths import *
+from pathlib import Path
+
+from unisync.argparser import create_argparser
+from unisync.errors import UnknownSSHError, unisync_exit_fatal
+from unisync.runners import unisync_sync, unisync_add, unisync_mount
+from unisync.config import load_config
+from unisync.synchroniser import Synchroniser
+from unisync.paths import PathsManager
 
 def main():
-    parser = create_argparser()
-    base_namespace = parser.parse_args()
+    parser = create_argparser(unisync_sync, unisync_add, unisync_mount)
+    cli_args = parser.parse_args()
 
-    config_path = os.path.expanduser("~/.config/unisync/config.ini")
-    if base_namespace.config != None and os.path.isfile(base_namespace.config):
-        config = load_config(base_namespace.config)
-    elif os.path.isfile(config_path):
-        config = load_config(config_path)
+    config_path: Path = Path("~/.config/unisync/config.ini").expanduser()
+    # Check if --config is set
+    if cli_args.config is not None and Path(cli_args.config).is_file():
+        config = load_config(cli_args.config)
+    elif config_path.is_file():
+        config = load_config(str(config_path))
     else:
-        # TODO make the command line arguments work and override the config options
-        pass
+        # TODO replace the next line with something to do if no config file is found
+        config = load_config(str(config_path))
+
+    # TODO: make the command line arguments work and override the config options
 
     synchroniser = Synchroniser(
             config.roots.remote,
@@ -28,23 +33,16 @@ def main():
             config.server.ip if config.server.ip != "" else config.server.hostname,
             config.server.port,
             config.unison.bools,
-            config.unison.values
+            config.unison.values,
+            backup=config.backup
     )
 
     paths_manager = PathsManager(Path(config.roots.local), config.other.cache_dir_path)
 
-    if synchroniser.create_ssh_master_connection() != 0:
-        print("Connection failed quitting")
-        return 1
-    print("Connected to the remote.")
-
-    #synchroniser.sync_files()
-    #synchroniser.update_links(background=False)
-    #synchroniser.mount_remote_dir()
-
-    synchroniser.close_ssh_master_connection()
-    print(paths_manager.get_paths_to_sync())
-
+    try:
+        cli_args.func(synchroniser, paths_manager, config)
+    except UnknownSSHError:
+        unisync_exit_fatal("Connection failed quitting")
 
 
 if __name__ == "__main__":

src/unisync/paths.py

@@ -1,4 +1,4 @@
-# Copyright (C) 2025 Paul Retourné
+# Copyright (C) 2025-2026 Paul Retourné
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 
@@ -92,7 +92,7 @@ class PathsManager:
         Writes a list of new paths to the file
         """
         current_paths = self.get_paths_to_sync()
-        paths_to_add = list()
+        paths_to_add = []
         # Check if one of the parent is already being synchronised
         # If so there is no need to add the child path
         for new_path in paths:
@@ -106,7 +106,7 @@ class PathsManager:
             if not is_contained and new_path not in paths_to_add:
                 paths_to_add.append(new_path)
 
-        with self.paths_file.open("w") as f:
+        with self.paths_file.open("a") as f:
             for p in paths_to_add:
                 f.write(p + "\n")
 

src/unisync/runners.py

@@ -0,0 +1,43 @@
+# Copyright (C) 2025-2026 Paul Retourné
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from unisync.synchroniser import Synchroniser
+from unisync.paths import PathsManager
+from unisync.config import Config
+
+
+def unisync_sync(synchroniser:Synchroniser, paths_manager:PathsManager, config: Config):
+    del config # The function signature must be the same for all runners
+
+    synchroniser.create_ssh_master_connection()
+    print("Connected to the remote.")
+
+    synchroniser.sync_files(paths_manager.get_paths_to_sync())
+    synchroniser.sync_links(paths_manager.get_paths_to_sync())
+
+    # TODO check the config options and do or don't do the following
+    synchroniser.update_links()
+    #synchroniser.mount_remote_dir()
+
+    synchroniser.close_ssh_master_connection()
+
+
+def unisync_add(synchroniser:Synchroniser, paths_manager:PathsManager, config: Config):
+    del config # The function signature must be the same for all runners
+
+    synchroniser.create_ssh_master_connection()
+    print("Connected to the remote.")
+
+    # TODO config or cli to skip this first sync
+    synchroniser.sync_files(paths_manager.get_paths_to_sync())
+
+    paths_manager.add_files_to_sync()
+    synchroniser.sync_files(paths_manager.get_paths_to_sync(), force=True)
+
+    synchroniser.close_ssh_master_connection()
+
+
+def unisync_mount(synchroniser:Synchroniser, paths_manager:PathsManager, config: Config):
+    del paths_manager # The function signature must be the same for all runners
+    del config # The function signature must be the same for all runners
+    synchroniser.mount_remote_dir()

src/unisync/synchroniser.py

@@ -1,6 +1,12 @@
-# Copyright (C) 2025 Paul Retourné
+# Copyright (C) 2025-2026 Paul Retourné
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+"""Exports the Synchroniser class.
+
+This class is used to perform all the actions that require a connection to
+the remote.
+"""
+
 import subprocess
 import os
 import sys
@@ -8,15 +14,47 @@ import time
 import logging
 
 from pathlib import Path
+from typing import cast
 
-from errors import RemoteMountedError, InvalidMountError
+from unisync.errors import RemoteMountedError, InvalidMountError, UnknownSSHError, FatalSyncError
+from unisync.config import BackupConfig
 
 logger = logging.getLogger(__name__)
 
 class Synchroniser:
+    """Synchroniser used to synchronise with a server.
 
-    def __init__(self, remote:str, local:str, user:str, ip:str,
-                 port:int=22, args_bool:list=[], args_value:dict={}, ssh_settings:dict={}):
+    It is used to perform every action needing a connection to the remote.
+    Create an ssh connection.
+    Perform the various synchronisation steps (files, links).
+    Update the links on the remote.
+    Mount the remote directory.
+    Close the ssh connection.
+
+    Attributes:
+        remote: The directory to synchronise to on the remote.
+        local: The directory to synchronise from locally.
+        user: The user on the remote server.
+        ip: The ip of the remote server.
+        port: The ssh port on the remote.
+        args_bool:
+            A list of boolean arguments for unison.
+            They will be passed directly to unison when calling it.
+            For example : auto will be passed as -auto
+        args_value:
+            Same as args_bool but for key value arguments.
+            Will be passed to unison as "-key value".
+        ssh_settings:
+            Settings to pass to the underlying ssh connection.
+            Currently unused.
+    """
+
+    def __init__(self, remote:str, local:str, user:str, ip:str, port:int=22,
+                 args_bool:list=[], args_value:dict={}, ssh_settings:dict={},
+                 backup:BackupConfig | None = None
+                 ):
+        """Initialises an instance of Synchroniser.
+        """
         self.remote_dir:str = remote
         self.local:str = local
         self.args_bool:list[str] = args_bool 
@@ -25,16 +63,56 @@ class Synchroniser:
         self.remote_user:str = user
         self.remote_ip:str = ip 
         self.remote_port:int = port
+        self.files_extra:list = list()
+        self.links_extra:list = list()
 
-    def create_ssh_master_connection(self, control_path:str="~/.ssh/control_%C", connection_timeout:int=60) -> int:
-        """
-        Creates an ssh master connection so the user only has to authenticate once to the remote server.
-        The subsequent connections will be made through this master connection which speeds up connecting.
-        @control_path: Set the location of the ssh control socket
-        @connection_timeout:
-            Time given to the user to authenticate to the remote server.
-            On slow connections one might want to increase this.
-        Returns 0 on success.
+        if(backup != None and backup.enabled):
+            backup = cast(BackupConfig, backup)
+            self.files_extra.append("-backup")
+            if(backup.selection != ""):
+                self.files_extra.append(backup.selection)
+            else:
+                self.files_extra.append("Name *")
+
+            self.files_extra.extend([
+                "-backuploc",
+                backup.location,
+                "-maxbackups",
+                str(backup.max_backups),
+                "-backupsuffix",
+                backup.backupsuffix,
+                "-backupprefix",
+                backup.backupprefix,
+                "-ignore",
+                f"Name {backup.backupprefix[:-1]}"
+            ])
+
+            self.links_extra.extend([
+                "-ignore",
+                f"Name {backup.backupprefix[:-1]}"
+                ])
+    
+    def create_ssh_master_connection(self, control_path:str="~/.ssh/control_%C", connection_timeout:int=60) -> None:
+        """Creates an ssh master connection.
+
+        It is used so the user only has to authenticate once to the remote server.
+        The subsequent connections will be made through this master connection
+        which speeds up connnection.
+        The users only have to enter their password once per synchronisation.
+
+        Args:
+            control_path: Set the location of the ssh control socket
+            connection_timeout:
+                Time given to the user to authenticate to the remote server.
+                On slow connections one might want to increase this.
+
+        Raises:
+            subprocess.TimeoutExpired:
+                The user didn't finish loging in in time.
+            KeyboardInterrupt:
+                The user interrupted the process.
+            UnknownSSHError:
+                An error occured during the connection.
         """
         self.control_path = os.path.expanduser(control_path)
         command = [
@@ -46,23 +124,25 @@ class Synchroniser:
                 "-p", str(self.remote_port)
                 ]
         master_ssh = subprocess.Popen(command)
+        # TODO: Raise an exception instead of changing the return value
         try:
             ret_code = master_ssh.wait(timeout=connection_timeout)
-        except subprocess.TimeoutExpired:
+        except subprocess.TimeoutExpired as e:
             print("Time to login expired", file=sys.stderr)
-            return 1
-        except KeyboardInterrupt:
-            return 2
+            raise e
+        except KeyboardInterrupt as e:
+            raise e
 
         if ret_code != 0:
             print("Login to remote failed", file=sys.stderr)
-            return ret_code
-        return 0
+            raise UnknownSSHError
 
 
     def close_ssh_master_connection(self) -> int:
-        """
-        Close the ssh master connection.
+        """Closes the ssh master connection.
+
+        Returns:
+            The return code of the ssh call.
         """
         command = [
                 "/usr/bin/ssh",
@@ -74,40 +154,68 @@ class Synchroniser:
         close = subprocess.Popen(command)
         return close.wait()
 
-    def sync_files(self, paths:list, force:bool=False) -> int:
+    def sync_files(self, paths:list, force:bool=False) -> None:
+        """Synchronises the files.
+
+        Args:
+            paths: List of paths to synchronise.
+            force: Force the changes from remote to local.
+
+        Raises:
+            FatalSyncError: A fatal error occured during the synchronisation.
         """
-        Synchronises the files.
-        """
-        return self.sync(
+
+        self.sync(
                 f"ssh://{self.remote_user}@{self.remote_ip}/{self.remote_dir}/.data",
                 self.local,
                 paths=paths,
-                force=force
+                force=force,
+                other=self.files_extra
                 )
 
-    def sync_links(self, ignore:list) -> int:
+    def sync_links(self, ignore:list) -> None:
+        """Synchronises the links, they must exist already.
+
+        Args:
+            ignore: List of paths to ignore.
+
+        Raises:
+            FatalSyncError: A fatal error occured during the synchronisation.
         """
-        Synchronises the links, they must exist already.
-        """
-        return self.sync(
+        self.sync(
                 f"ssh://{self.remote_user}@{self.remote_ip}/{self.remote_dir}/links",
                 self.local,
-                ignore=ignore
+                ignore=ignore,
+                other=self.links_extra
                 )
 
     def sync(self, remote_root:str, local_root:str,
-             paths:list=[], ignore:list=[], force:bool=False) -> int:
-        """
-        Perform the synchronisation by calling unison.
-        @remote_root: The remote root, must be a full root usable by unison.
-        @local_root: The local root, must be a full root usable by unison.
-        @paths: List of paths to synchronise
-        @ignore: List of paths to ignore
-            The paths and everything under them will be ignored.
-            If you need to ignore some specific files use the arguments.
-        @force: Force all changes from remote to local.
-            Used mostly when replacing a link by the file.
-        Returns: the unison return code see section 6.11 of the documentation
+             paths:list=[], ignore:list=[], force:bool=False,
+             other:list=[]
+             ) -> None:
+        """Performs the synchronisation by calling unison.
+
+        Args:
+            remote_root: The remote root, must be a full root usable by unison.
+            local_root: The local root, must be a full root usable by unison.
+            paths: List of paths to synchronise
+            ignore: List of paths to ignore
+                The paths and everything under them will be ignored.
+                If you need to ignore some specific files use the arguments.
+            force: Force all changes from remote to local.
+                Used mostly when replacing a link by the file.
+            other:
+                Other arguments to add to unison.
+                These arguments will only be used for this sync which is not
+                the case for the ones in self.args_bool and self.args_value.
+                They will be added to the command as is no - in front.
+                For exemple backups are implemented using this argument.
+
+        Raises:
+            FatalSyncError:
+                If unison returns 3 it means either a fatal error occured or the synchronisation
+                was interrupted.
+                If this happens propagate the error to unisync.
         """
         command = [ "/usr/bin/unison", "-root", remote_root, "-root", local_root ]
         for arg in self.args_bool:
@@ -117,6 +225,7 @@ class Synchroniser:
             command.append(value)
 
         sshargs = f"-p {self.remote_port} "
+        sshargs += f"-S {self.control_path} "
         for arg, value in self.ssh_settings.items():
             sshargs += arg + " " + value + " "
         command.append("-sshargs")
@@ -131,21 +240,26 @@ class Synchroniser:
             command.append(f"BelowPath {path}")
 
         if force:
-            command.append("-force")
+            command.append("-prefer")
             command.append(remote_root)
             command.append("-batch")
 
+        for arg in other:
+            command.append(arg)
+
         proc = subprocess.Popen(command)
         ret_code = proc.wait()
-        return ret_code
+        if ret_code == 3:
+            raise FatalSyncError("Synchronisation could not be completed")
 
     def update_links(self, background:bool=True):
-        """
-        Update the links on the remote.
+        """Updates the links on the remote.
+
         First calls cleanlinks to remove deadlinks and empty directories.
         Then calls lndir to create the new links.
+
         Args:
-        - background: controls if the update is done in the background or waited for
+            background: controls if the update is done in the background or waited for.
         """
 
         link_update_script = (f"cd {self.remote_dir}/links && "
@@ -165,7 +279,7 @@ class Synchroniser:
                 link_background_wrapper
                 ]
 
-        link_update_process = subprocess.Popen(command, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+        link_update_process = subprocess.run(command, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
 
         if not background:
             print("Starting links update.")
@@ -173,13 +287,14 @@ class Synchroniser:
             print("Done")
 
     def mount_remote_dir(self):
-        """
-        Mount the remote directory to make the local links work.
-        This is achieved using sshfs.
-        Raise:
-        - RemoteMountedError: The .data directory is already a mount point
-        - InvalidMountError: .data is either not a directory or not empty
-        - subprocess.CalledProcessError: An error occured with sshfs
+        """Mounts the remote directory to make the local links work.
+
+        This is achieved using sshfs which may fail.
+
+        Raises:
+            RemoteMountedError: The .data directory is already a mount point.
+            InvalidMountError: .data is either not a directory or not empty.
+            subprocess.CalledProcessError: An error occured with sshfs.
         """
         # Get the absolute path to the correct .data directory resolving symlinks
         path_to_mount:Path = Path(f"{self.local}/../.data").resolve()

tests/runners.py

@@ -0,0 +1,8 @@
+# Copyright (C) 2026 Paul Retourné
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from unisync.synchroniser import Synchroniser
+from unisync.paths import PathsManager
+
+def unisync_test(synchroniser:Synchroniser, paths_manager:PathsManager):
+    print("Testing")

tests/test.py

@@ -0,0 +1,39 @@
+# Copyright (C) 2026 Paul Retourné
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+import os
+from pathlib import Path
+
+from unisync.argparser import create_argparser
+from unisync.runners import unisync_sync, unisync_add, unisync_mount
+from unisync.config import load_config
+from unisync.synchroniser import Synchroniser
+from unisync.paths import *
+
+from runners import *
+
+def main():
+    parser = create_argparser(unisync_test, unisync_add, unisync_mount)
+    cli_args = parser.parse_args()
+
+    config_path = os.path.expanduser("./config.ini")
+    config = load_config(config_path)
+
+    print(config)
+
+    synchroniser = Synchroniser(
+            config.roots.remote,
+            config.roots.local,
+            config.server.user,
+            config.server.ip if config.server.ip != "" else config.server.hostname,
+            config.server.port,
+            config.unison.bools,
+            config.unison.values
+    )
+
+    paths_manager = PathsManager(Path(config.roots.local), config.other.cache_dir_path)
+
+    cli_args.func(synchroniser, paths_manager)
+
+if __name__ == "__main__":
+    main()