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U3d is a set of tools to interact with Unity from command line. It is available on Linux, Macintosh and Windows.

What can it do?

U3d provides help for running and installing unity from CLI.

U3d knows about your Unity project and behaves differently if invoked from within a Unity project directory. For example, it can run or download the version required by your project without you having to specify it. It also makes it easy to run several Unity instances in parallel.

Available commands are:

  • u3d available: List download-ready versions of Unity

u3d available

  • u3d install: Download (and/or) install Unity editor packages

u3d install

  • u3d uninstall: Uninstall Unity versions

u3d uninstall

  • u3d list: List installed versions of Unity

u3d list

  • u3d run: Run Unity, and parses its output through u3d's log prettifier

Here we start with the proper version of Unity:

u3d run without arguments

Here we pass some arguments:

u3d run with arguments

The prettifyer is on by default but can be turned off to get Unity's raw output.

  • u3d prettify: Prettify a saved editor logfile

    Information on how prettify works

  • u3d dependencies: [Linux] Install dependencies that Unity don't install by default on Linux

  • u3d licenses: display information about your Unity licenses

u3d list

  • u3d console: Run u3d in interactive mode, accessing its API

u3d console


gem install u3d


u3d requires some environment variables set up to run correctly. In particular processing log files requires your locales to be set to a UTF-8 locale. In your shell profile add the following lines:

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8

You can find your shell profile at ~/.bashrc, ~/.bash_profile or ~/.zshrc depending on your system.

Central cache

Because fetching all the versions online can be rather long, especially on slow connections, u3d uses a central cache which performs the fetching automatically and makes retrieving all the versions much faster.

NOTE: If you do not want to use the central cache for some reason, you can still perform the version fetching manually by running u3d available --no-central which will cache locally the versions that you retrieved so that you can use them later (in u3d install for example).

Unity versions numbering

Unity uses the following version formatting: 0.0.0x0. The 'x' can takes different values:

  • 'f' are the main release candidates for Unity
  • 'p' are patches fixing those releases
  • 'b' are the beta releases
  • 'a' are the alpha releases (not currently discovered online)

Some versions are known to have a different numbering, e.g. Linux 2017.1.0f3 is named 2017.1.0xf3Linux. Its ProjectSettings/ProjectVersion.txt will contain the Linux specific version.

When referencing to a version on the CLI, u3d normalizes these weird versions. For example, if you ask u3d to launch unity 2017.1.0f3 on Linux, you can use u3d -u 2017.1.0f3 and it will find "2017.1.0xf3Linux".

Unity build numbers

Every Unity version has a build number in the form of a 12 characters hexadecimal (e.g. bf5cca3e2788). You might have noticed them: those build numbers are currently part of the download URLs that u3d available displays.

Most of the time Unity users won't have to pay attention to build numbers. In a few scenarios, they become important.

For example, sometimes Unity releases multiple builds with the same version but different build numbers, e.g. when releasing hot fixes. If you need a hotfix release, you might need to ensure that you are using it.

Right now u3d has light support for build numbers. The build number can be found inside the Unity installation files and u3d will extract them and u3d list will display both the version and the build number. In the future u3d will have more features to help you managing installations of those special builds. Follow this request for enhancement for more information.

Default Installation paths

The standard Unity installer has some quirks:

  • on Mac, it always installs Unity on /Applications/Unity. If you want to add a module to a particular version, you will have to move the unity you are trying to extend to that particular location

  • on Linux, most versions are installed as unity-editor-$version with version following the 'standard' numbering (except for some weird versions, see above). Unity lets you install the program in the directory of your choice

Also for easing discoverability, it is recommended that you install your Unity versions in a similar area.

For these reasons, u3d has standardized the installation paths of the Unity version it installs.

  • on Mac, versions are installed under /Applications/Unity_$version
  • on Linux, versions are installed under /opt/unity-editor-$version
  • on Windows, versions are installed under C:/Program Files/Unity_$version

u3d should be able to find the different unity installed under those locations. If the Unity installations are not in those locations, u3d might not find them automatically.

Sanitize / standardize Unity installation paths

If you have installed Unity in different locations, u3d might discover them and propose you to move them to its standard location. The procedure should be self described and easily revertible (manually). This sanitization operation is only proposed in interactive mode (i.e. if you are not using u3d unattended, e.g. in a build script on a CI server) when running the list command.

u3d sanitize

If you wish a particular Unity installation to be ignored by the sanitization feature, create a .u3d_do_not_move file inside it.

If you wish to have your pre-installed unities directory name to automatically contain the full version (unity version + build number), you can call u3d move --long <version>.


When you install Unity with this tool, you will have to grant it higher privileges so it can perform the installation. It means that under MacOS and Linux, you will be asked for your sudo password.

On Windows, you must launch an administrative command interface to be able to run install without the --no-install option. Same goes for any kind of sanitization where u3d would move files around.


  • List installed versions on your computer:
u3d list
  • List versions you can download and install from Unity, as well as their packages, on Mac:
u3d available -p -o mac
  • Download and install version 5.6.0f3 of Unity with its documentation and the WebPlayer package:
u3d install 5.6.0f3 -p Unity,Documentation,WebPlayer
  • Download version 5.6.0f3 of Unity without installing it:
u3d install 5.6.0f3 --no-install
  • Install previously downloaded version 5.6.0f3:
u3d install 5.6.0f3 --no-download
  • Run a CLI on the current project given the project's configured unity version, displaying prettified logs, while keeping the original logs under editor.log:
u3d run -- -batchmode -quit -logFile `pwd`/editor.log -executeMethod "WWTK.SimpleBuild.PerformAndroidBuild"
  • Open the proper Unity for the current project, displaying the raw editor logs in the command line:
u3d run -r

You can get further information on how to use U3d by running u3d --help (or u3d -h).


Run several Unity instances in parallel

The only thing you have to watch for while trying to run multiple instances of Unity in parallel is the fact that they will share the same log file by default (the Editor.log). Therefore you will have to specify it using the command line arguments, you can do so with u3d the following way from each of your project root folder:

u3d run -- -logFile /path/to/your/logfile

NOTE: You still won't be able to overcome the fact that Unity cannot launch the same project twice. This only applies to running multiple Unity instances for different projects.

Reuse u3d install on a CI environment

Here you have multiple options

  • pass the password using U3D_PASSWORD environment variable

  • if on Mac, use the keychain option (you set it before hand on the machine, e.g. from the command line using u3d credentials add (use u3d credentials check to verify) and then use u3d install -k to activate the keychain while installing.

For more information see also how to use u3d to install Unity on a CI server.

Install ruby

  • On MacOS and Linux:

Your usual package manager should be available to install it easily for you. On UNIX systems, we recommend you use RVM (Ruby Version Manager), which lets you manage several versions of Ruby.

  • On Windows:

Installing Ruby on Windows is a bit more complicated than installing it on Linux or Mac. You have several options available: Bash on Ubuntu on Windows (see further note), Cygwin but we recommend you use the Ruby Installer for Windows.

NOTE: We do not support Bash on Ubuntu on Windows. Most features of u3d will not work as intended on this platform and we therefore strongly advice you against using u3d on it.


Use the global --verbose argument to enable debug logs.

Use the global -t argument to display stack traces if a crash occurs.

Solve SSL Errors

If you face an issue similar to this one

SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed

your ruby setup to work with OpenSSL probably needs to be fixed.

  • On MacOS:

Your version of OpenSSL may be be outdated, make sure you are using the last one.

  • On Windows:

A fix to the issue stated above has been found on StackOverflow. If you follow the steps described in this topic, you will most likely get rid of this issue.

Solve Connection failures

If your network is flaky you might try to change the way u3d uses ruby's Net::HTTP trsnsport mechanism

  • set U3D_HTTP_READ_TIMEOUT (defaults 300 seconds) to change the http read timeout

  • U3D_HTTP_MAX_RETRIES (ruby 2.5 only, defaults 1). Ruby automatically retries once upon failures on idempotents methods. From ruby 2.5. you can change the number of time ruby might retry.