Installing and Updating

Automated installation

To install the most recent version of Loom, change to your project directory and enter:

curl -s | sh

The same command is also used to update an existing installation.

If no errors were reported, Loom is installed to your system / project.

If you want to install a specific (older) version of loom instead (e.g. 1.0.0), enter:

curl -s | sh -s 1.0.0

Source Control Management

If you’re using a SCM system like Git, you probably want to add the Loom Launcher and the Loom Installer to your repository to ensure reproducible builds for your project:

git add loom loom.cmd loom-installer

Furthermore, you probably want to exclude some directories from being committed. Example .gitignore file:


# In case .jar files are globally ignored

Behind the scenes

To guarantee reproducible builds while maintaining the size of files added to your project at a minimum, the Loom installation is split into two parts: a project wide one (the Loom Installer and the Loom Launcher) and a system wide one (the Loom Library).

After a successful run, the following files were created:

In your project directory:

The Loom Installer – a tiny program that installs Loom on systems where it is missing. It is executed by the Loom Launcher if necessary.
Configuration of the Loom Installer – e.g. the download URL of Loom and its version.
The Loom Launcher for Unix
The Loom Launcher for Windows

In your system:

The Loom Library is installed to a user specific directory on your machine, that is dependent on your operating system:

  • On Unix: ~/.loom/
  • On Windows: %LOCALAPPDATA%\Loom\Loom\ (where %LOCALAPPDATA% is C:\Users\{username}\AppData\Local by default)

You can override these operating system specific defaults by setting the LOOM_USER_HOME environment variable to a directory of your choice.

Manual installation

If you want to install Loom manually (discouraged), follow these steps:

  • Change to your project directory
  • Create a directory named loom-installer
  • Create a file named loom-installer/, which points to the Loom Library URL (example: distributionUrl=
  • Download the Loom Installer to a file named loom-installer/loom-installer.jar. You can download it from
  • Launch the Loom Installer by entering java -jar loom-installer/loom-installer.jar .