Git submodule inside of a submodule (nested submodules)

As Sridhar comments below, from Git1.6.5+, git clone --recursive is now the official alternative, described in:

• "git clone --submodule"
• "Retrospectively add --recursive to a git repo"
  (with the alias $ git config --global alias.cloner = 'clone --recursive', which avoids shadowing the normal git clone command)

inamiy correctly points out the git submodule update --init --recursive command, introduced in commit b13fd5c, again in git1.6.5, by Johan Herland (jherland).

And IceFire adds in the comments:

If you would like to checkout only one submodule of a submodule, then
git submodule update --init <submoduleName> is the way to go.

---

(older original answer)

According to the manual page

 git submodule update --recursive

should update any nested submodules. But the init part may not be recursive.

Depending on your version of Git, you could fall back to a more "scripting" approach, with this article Recursively Updating Git Submodules which allows for recursive init and update:

#!/usr/bin/perl

use strict;
use Cwd;

init_and_update();

exit;

sub init_and_update
{
    my $start_path = cwd();

    my %paths;
    my $updated;

    do
    {
        my $data = `find . -name '.gitmodules'`;
        chomp($data);

        $data =~ s/\/\.gitmodules//g;

        foreach my $path (split(/\n/, $data))
        {
            $paths{$path} = '' if($paths{$path} eq '');
        }

        $updated = 0;

        foreach my $path (sort keys %paths)
        {
            if($paths{$path} eq '')
            {
                chdir($path);
                `git submodule init 2>&1`;
                `git submodule update 2>&1`;
                chdir($start_path);

                if($ARGV[0] eq '--remove-gitmodules')
                {
                    unlink("$path/.gitmodules");
                }

                $paths{$path} = 1;

                $updated++;
            }
        }
    } while($updated);
}

As mentioned in Retrospectively add --recursive to a git repo

git submodule update --init --recursive

should work.