tsync

tsync keeps copies of individual files synchronized across local disks, external drives, and USB devices on macOS and Linux.

• Changes made at any configured location are copied to the others.
• Missing drives are skipped and reconciled after they reappear.
• Writes use an atomic rename to avoid exposing partial files.
• launchd and systemd run tsync automatically in the background.

Configuration

Create ~/.config/tsync/config.json before installing:

{
  "source_path": "/Users/j/Documents/hello.txt",
  "paths": [
    "/Users/j/Downloads/hello.txt",
    "/Volumes/USB/hello.txt"
  ],
  "conflict_policy": "newest_wins"
}

All paths must be absolute. Destination files may be absent, but their parent directories must exist. tsync deliberately does not create missing parent directories because doing so could hide the fact that a removable drive is not mounted.

For more than one independent file:

{
  "reconcile_interval": "2s",
  "syncs": [
    {
      "source_path": "/Users/j/Documents/hello.txt",
      "paths": ["/Volumes/USB/hello.txt"],
      "conflict_policy": "newest_wins"
    },
    {
      "source_path": "/Users/j/.ssh/config",
      "paths": ["/Volumes/Backup/ssh-config"],
      "conflict_policy": "source_wins"
    }
  ]
}

Policies:

• newest_wins (default): a changed file is propagated to every location; startup and remount conflicts use the newest modification time.
• source_wins: source_path is authoritative and overwrites changes made to its copies.

Install

Release installation also registers and starts a per-user launchd or systemd service. The configuration must exist and pass validation first.

curl -fsSL https://raw.githubusercontent.com/0jc1/tsync/main/install.sh -o install-tsync.sh
sh install-tsync.sh
rm install-tsync.sh

The default binary location is ~/.local/bin/tsync. Use a different config or install a system service with:

sh install-tsync.sh --config /path/to/config.json
sudo sh install-tsync.sh --scope system --config /etc/tsync/config.json

System installation places the binary in /usr/local/bin. Uninstallation preserves configuration:

sh install-tsync.sh --uninstall
sudo sh install-tsync.sh --scope system --uninstall

CLI

tsync                         Run the sync process
tsync status                  Show runtime status
tsync validate                Validate the configuration
tsync help                    Show help
tsync version                 Show the version
tsync --config PATH validate  Use another configuration file

Running tsync without a command is how the startup service launches it.

Native service controls

macOS user service:

launchctl kickstart -k "gui/$(id -u)/com.tsync.agent"
launchctl bootout "gui/$(id -u)" "$HOME/Library/LaunchAgents/com.tsync.agent.plist"

Linux user service:

systemctl --user status tsync
systemctl --user restart tsync
systemctl --user stop tsync

After changing the configuration, restart the service.

Build from source

go build -o tsync .
go test ./...

Building the binary directly does not register a startup service.