Externals is a project that allows you to use the workflow normally made possible by svn:externals in an SCM independent manner.

Please report bugs to github.com/azimux/externals/issues

I was inspired to create this project because I had several projects that had a mix of plugins managed by git and by svn. Git's submodule feature is not exactly like svn:externals. Basically, I don't like how you have to manually checkout a branch, and I don't like git status not propagating through the submodules. Also, the branch tip doesn't automatically move with git-submodule. Subversion always checks out the branch tip for subprojects when performing a checkout or update.

Externals is designed such that adding support for a new SCM, or new project types is easy.

The externals executable is called ext. Commands come in a long form and a short form. The longer form applies the action to the main project. The short forms apply the action to all sub projects.

There's a tutorial available at nopugs.com/ext-tutorial

The commands and usage are as follows (from 'ext help'):

ext [OPTIONS] <command> [repository] [-b <branch>] [path]

    --svn, --subversion  same as '--scm svn' Uses subversion to
                         checkout/export the main project
-g, --git                same as '--scm git' Uses git to checkout/export the
                         main project
-t, --type TYPE          The type of project the main project is. For example,
-s, --scm SCM            The SCM used to manage the main project. For example,
                         '--scm svn'.
-b, --branch BRANCH      The branch you want the subproject to checkout when
                         doing 'ext install'
-r, --revision REVISION  The revision you want the subproject to checkout when
                         doing 'ext install'
-f, --force_removal      When doing an uninstall of a subproject, remove it's
                         files and subfolders, too.
-w, --workdir DIR        The working directory to execute commands from. Use
                         this if for some reason you cannot execute ext from
                         the main project's directory (or if it's just
                         inconvenient, such as in a script or in a Capistrano
    --help               does the same as 'ext help' If you use this with a
                         command it will ignore the command and run help
    --version            Displays the version number of externals and then
                         exits. Same as 'ext version'

Commands that apply to the main project or the .externals file: freeze, help, init, install, switch, touch_emptydirs, unfreeze, uninstall, update_ignore, version

freeze Usage: ext freeze <subproject> [REVISION]

Locks a subproject into a specific revision/branch.  If no
revision is supplied, the current revision/branch of the
project will be used.  You can specify the subproject by name
or path.

help It helps. Hopefully.

init Creates a .externals file containing only [main]

It will try to determine the SCM used by the main project,
as well as the project type.  You don't have to specify
a project type if you don't want to or if your project type
isn't supported.  It just means that when using 'install'
that you'll want to specify the path.

install Usage: ext install <repository> [-b <branch>] [path]

Registers <repository> in .externals under the appropriate
SCM.  Checks out the project, and also adds it to the ignore
feature offered by the SCM of the main project.  If the SCM
type is not obvious from the repository URL, use the --scm,
--git, or --svn flags.

switch Usage: ext switch <branch_name>

Changes to the named branch <branch_name> and updates any
subprojects and applies any changes that have been made to the
.externals file.

touch_emptydirs Recurses through all directories from the

top and adds a .emptydir file to any empty directories it
comes across.  Useful for dealing with SCMs that refuse to
track empty directories (such as git, for example)

unfreeze Usage: ext unfreeze <subproject>

Unfreezes a previously frozen subproject.  You can specify
the subproject by name or path.

uninstall Usage: ext uninstall [-f|–force_removal] <project>

Removes a subproject from being tracked by ext.  If you
want the files associated with this subproject deleted as well
(if, for example, you wish to reinstall it from a different
repository) then you can use the -f option to remove the files.

update_ignore Adds all paths to subprojects that are

registered in .externals to the ignore feature of the
main project.  This is automatically performed by install,
and so you probably only will run this if you are manually
maintaining .externals

version Displays the version number of externals and exits.

Commands that apply to the main project and all subprojects: checkout, export, status, update

checkout Usage: ext checkout <repository>

Checks out <repository>, and checks out any subprojects
registered in <repository>'s .externals file.

export Usage: ext export <repository>

Like checkout except this command fetches as little
history as possible.

status Usage: ext status

Prints out the status of the main project, followed by
the status of each subproject.

update Usage: ext update

Brings the main project, and all subprojects, up to the
latest version.

Commands that only apply to the subprojects: co, ex, st, up

co Like checkout, but skips the main project and

only checks out subprojects.

ex Like export, but skips the main project.

st Like status, but skips the main project.

up Like update, but skips the main project.


Sometimes it's convenient to have options passed to the underlying scm executable, like –trust-certid to svn, etc. This can be done by editing the .externals file. You can put scm_opts = <options> under the project you want, and it will be passed whenever externals calls the executable. You can specify an option to only be ran when doing co/ex/st/up by adding _co/_ex/_st/_up to the scm_opts option.



scm = git scm_opts = –verbose


scm = svn scm_opts = –trust-certid scm_opts_co = –non-interactive

This type of a .externals file tells externals to pass “ –non-interactive –trust-certid” to svn when doing a checkout of some_plugin. “–trust-certid” will be sent to all other calls to svn dealing with some_plugin. “–verbose” will be passed to git on all calls dealing with the main project.

You can pass options globally by setting <scm_name>_opts in the main project.



scm = svn svn_opts = –trust-certid svn_opts_co = –non-interactive


scm = svn

This will pass “–non-interactive –trust-certid” to all co calls dealing with subversion projects, regardless of which project it is.


Subversion does not have a branch feature. Instead, subversion users use the copy feature to copy directories within the repository (branch), a switch command to switch the URL that the working directory points at (checkout), and a merge feature to merge directories (merge).

ext handles branches in Subversion by splitting the URL given by 'svn info' into a repository part and a branch part.

If you find yourself doing this:

ext checkout svn+ssh://someserver/somepath/repository/branches/new_feature

Then you almost certainly mean to do this:

ext checkout svn+ssh://someserver/somepath/repository -b branches/new_feature

For ext to use branch-related features with Subversion repositories, the repository must be known. For subprojects this is never a problem, but for the main project, it's important that there is a repository field under [.] in the .externals file. This can be accomplished by using -b with commands like 'ext checkout' and 'ext init' or by manually editing the .externals file.


Tests are ran with:

rake test

You will need git and svn installed. If you are using Ruby 1.9 to run the tests, you will need to have the simplecov gem installed.

Copyright Information

The externals project is copyright 2008 by Miles Georgi and is released under the MIT license.

The license is available in the same directory as this README file and is named MIT_LICENSE.txt