14 files changed, 118 insertions, 6 deletions
diff --git a/docs/en/erlang.mk/1/guide/app.asciidoc b/docs/en/erlang.mk/1/guide/app.asciidoc
index 9d5e9488..226f24c4 100644
--- a/docs/en/erlang.mk/1/guide/app.asciidoc
+++ b/docs/en/erlang.mk/1/guide/app.asciidoc
@@ -25,6 +25,20 @@ and conventions. Most of the conventions come from Erlang/OTP
 itself so any seasoned Erlang developers should feel right at
 home.
 
+Erlang.mk supports multi-threaded building. Parallel execution
+is supported for all targets. To execute Erlang.mk in parallel
+the `-j` option must be used:
+
+[source,bash]
+$ make -j8
+
+The `MAKEFLAGS` variable can be used to enable parallel
+building permanently on your system. It can be set in
+your `.zshrc`, `.bashrc` or equivalent file.
+
+[source,bash]
+MAKEFLAGS="-j8"
+
 === What to build
 
 Erlang.mk gives you control over three steps of the build
diff --git a/docs/en/erlang.mk/1/guide/app/index.html b/docs/en/erlang.mk/1/guide/app/index.html
index 13875dda..205542e0 100644
--- a/docs/en/erlang.mk/1/guide/app/index.html
+++ b/docs/en/erlang.mk/1/guide/app/index.html
@@ -74,6 +74,20 @@ http://www.gnu.org/software/src-highlite -->
 </div></div>
 <p>It will work regardless of your project: OTP applications, library applications, NIFs, port drivers or even releases. Erlang.mk also automatically downloads and compiles the dependencies for your project.</p>
 <p>All this is possible thanks to a combination of configuration and conventions. Most of the conventions come from Erlang/OTP itself so any seasoned Erlang developers should feel right at home.</p>
+<p>Erlang.mk supports multi-threaded building. Parallel execution is supported for all targets. To execute Erlang.mk in parallel the <code>-j</code> option must be used:</p>
+<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
+by Lorenzo Bettini
+http://www.lorenzobettini.it
+http://www.gnu.org/software/src-highlite -->
+<pre><tt>$ make -j<font color="#993399">8</font></tt></pre>
+</div></div>
+<p>The <code>MAKEFLAGS</code> variable can be used to enable parallel building permanently on your system. It can be set in your <code>.zshrc</code>, <code>.bashrc</code> or equivalent file.</p>
+<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
+by Lorenzo Bettini
+http://www.lorenzobettini.it
+http://www.gnu.org/software/src-highlite -->
+<pre><tt><font color="#009900">MAKEFLAGS</font><font color="#990000">=</font><font color="#FF0000">"-j8"</font></tt></pre>
+</div></div>
 <h2 id="_what_to_build">What to build</h2>
 <p>Erlang.mk gives you control over three steps of the build process, allowing you to do a partial build if needed.</p>
 <p>A build has three phases: first any dependency is fetched and built, then the project itself is built and finally a release may be generated when applicable. A release is only generated for projects specifically configured to do so.</p>
diff --git a/docs/en/erlang.mk/1/guide/common_test.asciidoc b/docs/en/erlang.mk/1/guide/common_test.asciidoc
index f8f0de3d..993bb8cd 100644
--- a/docs/en/erlang.mk/1/guide/common_test.asciidoc
+++ b/docs/en/erlang.mk/1/guide/common_test.asciidoc
@@ -93,5 +93,11 @@ as a dependency, you can run the following directly:
 [source,bash]
 $ make -C deps/cowboy ct-http t=http_compress
 
+The variable `c` can be used to run a specific test when
+the test suite does not group test cases:
+
+[source,bash]
+$ make ct-http c=headers_dupe
+
 Finally, xref:coverage[code coverage] is available,
 but covered in its own chapter.
diff --git a/docs/en/erlang.mk/1/guide/common_test/index.html b/docs/en/erlang.mk/1/guide/common_test/index.html
index 8c4c66d2..c50f40be 100644
--- a/docs/en/erlang.mk/1/guide/common_test/index.html
+++ b/docs/en/erlang.mk/1/guide/common_test/index.html
@@ -146,6 +146,13 @@ http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
 <pre><tt>$ make -C deps/cowboy ct-http <font color="#009900">t</font><font color="#990000">=</font>http_compress</tt></pre>
 </div></div>
+<p>The variable <code>c</code> can be used to run a specific test when the test suite does not group test cases:</p>
+<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
+by Lorenzo Bettini
+http://www.lorenzobettini.it
+http://www.gnu.org/software/src-highlite -->
+<pre><tt>$ make ct-http <font color="#009900">c</font><font color="#990000">=</font>headers_dupe</tt></pre>
+</div></div>
 <p>Finally, <a href="../coverage">code coverage</a> is available, but covered in its own chapter.</p>
 
 
diff --git a/docs/en/erlang.mk/1/guide/deps.asciidoc b/docs/en/erlang.mk/1/guide/deps.asciidoc
index 84a53de1..3ba7a398 100644
--- a/docs/en/erlang.mk/1/guide/deps.asciidoc
+++ b/docs/en/erlang.mk/1/guide/deps.asciidoc
@@ -163,6 +163,7 @@ The following table lists all existing methods:
 |===
 | Name           | Format          | Description
 | git            | git repo commit | Clone the Git repository and checkout the given version
+| git-subfolder  | git repo commit subfolder | Clone the Git repository, checkout the given version and use one of its subfolders as a dependency
 | git-submodule  | git-submodule   | Initialize and update the Git submodule
 | hg             | hg repo commit  | Clone the Mercurial repository and update to the given version
 | svn            | svn repo        | Checkout the given SVN repository
@@ -514,6 +515,28 @@ projects using the `NO_AUTOPATCH` variable:
 [source,make]
 NO_AUTOPATCH = cowboy ranch cowlib
 
+=== Dealing with duplicate modules
+
+When there are duplicate modules found in both applications
+and their dependencies, some tasks may fail. Erlang expects
+modules to be unique in general.
+
+When the duplicates are found in dependencies, you will need
+to remove one of the duplicates at fetch time. To do so, you
+can add a rule similar to this to your Makefile before including
+'erlang.mk':
+
+[source,make]
+----
+DEPS_DIR = $(CURDIR)/deps
+
+deps:: $(DEPS_DIR)/cowlib
+	$(verbose) rm -f $(DEPS_DIR)/cowlib/src/cow_ws.erl
+----
+
+This must be done from the application that has this dependency.
+Only define the `DEPS_DIR` variable if necessary.
+
 === Skipping deps
 
 It is possible to temporarily skip all dependency operations.
diff --git a/docs/en/erlang.mk/1/guide/deps/index.html b/docs/en/erlang.mk/1/guide/deps/index.html
index 44c325d0..11e9171f 100644
--- a/docs/en/erlang.mk/1/guide/deps/index.html
+++ b/docs/en/erlang.mk/1/guide/deps/index.html
@@ -187,6 +187,10 @@ http://www.gnu.org/software/src-highlite -->
 <td>git repo commit</td>
 <td>Clone the Git repository and checkout the given version</td>
 </tr>
+<tr><td>git-subfolder</td>
+<td>git repo commit subfolder</td>
+<td>Clone the Git repository, checkout the given version and use one of its subfolders as a dependency</td>
+</tr>
 <tr><td>git-submodule</td>
 <td>git-submodule</td>
 <td>Initialize and update the Git submodule</td>
@@ -426,6 +430,19 @@ http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
 <pre><tt><font color="#009900">NO_AUTOPATCH =</font> cowboy ranch cowlib</tt></pre>
 </div></div>
+<h2 id="_dealing_with_duplicate_modules">Dealing with duplicate modules</h2>
+<p>When there are duplicate modules found in both applications and their dependencies, some tasks may fail. Erlang expects modules to be unique in general.</p>
+<p>When the duplicates are found in dependencies, you will need to remove one of the duplicates at fetch time. To do so, you can add a rule similar to this to your Makefile before including <em>erlang.mk</em>:</p>
+<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
+by Lorenzo Bettini
+http://www.lorenzobettini.it
+http://www.gnu.org/software/src-highlite -->
+<pre><tt><font color="#009900">DEPS_DIR =</font> <font color="#009900">$(CURDIR)</font>/deps
+
+<font color="#990000">deps::</font> <font color="#009900">$(DEPS_DIR)</font>/cowlib
+	<font color="#009900">$(verbose)</font> rm -f <font color="#009900">$(DEPS_DIR)</font>/cowlib/src/cow_ws.erl</tt></pre>
+</div></div>
+<p>This must be done from the application that has this dependency. Only define the <code>DEPS_DIR</code> variable if necessary.</p>
 <h2 id="_skipping_deps">Skipping deps</h2>
 <p>It is possible to temporarily skip all dependency operations. This is done by defining the <code>SKIP_DEPS</code> variable. Use cases include being somewhere with no connection to download them, or perhaps a peculiar setup.</p>
 <p>A typical usage would be:</p>
diff --git a/docs/en/erlang.mk/1/guide/edoc.asciidoc b/docs/en/erlang.mk/1/guide/edoc.asciidoc
index 9fc1a740..2992a37d 100644
--- a/docs/en/erlang.mk/1/guide/edoc.asciidoc
+++ b/docs/en/erlang.mk/1/guide/edoc.asciidoc
@@ -46,3 +46,16 @@ the following to your Makefile:
 ----
 docs:: edoc
 ----
+
+=== Running EDoc on all applications
+
+In a multi-application project you may want to run EDoc
+against all applications at the same time, instead of
+against each applications independently. To do so, you
+need to configure the `EDOC_SRC_DIRS` at the end of
+your Makefile, after including 'erlang.mk':
+
+[source,make]
+----
+EDOC_SRC_DIRS = $(ALL_APPS_DIRS)
+----
diff --git a/docs/en/erlang.mk/1/guide/edoc/index.html b/docs/en/erlang.mk/1/guide/edoc/index.html
index 513cb07f..ff876b37 100644
--- a/docs/en/erlang.mk/1/guide/edoc/index.html
+++ b/docs/en/erlang.mk/1/guide/edoc/index.html
@@ -98,6 +98,14 @@ http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
 <pre><tt><font color="#990000">docs::</font> edoc</tt></pre>
 </div></div>
+<h2 id="_running_edoc_on_all_applications">Running EDoc on all applications</h2>
+<p>In a multi-application project you may want to run EDoc against all applications at the same time, instead of against each applications independently. To do so, you need to configure the <code>EDOC_SRC_DIRS</code> at the end of your Makefile, after including <em>erlang.mk</em>:</p>
+<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
+by Lorenzo Bettini
+http://www.lorenzobettini.it
+http://www.gnu.org/software/src-highlite -->
+<pre><tt><font color="#009900">EDOC_SRC_DIRS =</font> <font color="#009900">$(ALL_APPS_DIRS)</font></tt></pre>
+</div></div>
 
 
 
diff --git a/docs/en/erlang.mk/1/guide/eunit.asciidoc b/docs/en/erlang.mk/1/guide/eunit.asciidoc
index 496b6749..41e26e39 100644
--- a/docs/en/erlang.mk/1/guide/eunit.asciidoc
+++ b/docs/en/erlang.mk/1/guide/eunit.asciidoc
@@ -65,7 +65,7 @@ to be passed to `erl` when running EUnit tests. For example,
 you can load the 'vm.args' and 'sys.config' files:
 
 [source,make]
-EUNIT_ERL_OPTS = -args_file rel/vm.args -config rel/sys.config
+EUNIT_ERL_OPTS = -args_file config/vm.args -config config/sys.config
 
 === Usage
 
diff --git a/docs/en/erlang.mk/1/guide/eunit/index.html b/docs/en/erlang.mk/1/guide/eunit/index.html
index ba47b6c2..502c76da 100644
--- a/docs/en/erlang.mk/1/guide/eunit/index.html
+++ b/docs/en/erlang.mk/1/guide/eunit/index.html
@@ -104,7 +104,7 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-<pre><tt><font color="#009900">EUNIT_ERL_OPTS =</font> -args_file rel/vm.args -config rel/sys.config</tt></pre>
+<pre><tt><font color="#009900">EUNIT_ERL_OPTS =</font> -args_file config/vm.args -config config/sys.config</tt></pre>
 </div></div>
 <h2 id="_usage">Usage</h2>
 <p>To run all tests (including EUnit):</p>
diff --git a/docs/en/erlang.mk/1/guide/installation.asciidoc b/docs/en/erlang.mk/1/guide/installation.asciidoc
index 3298db2d..254b461d 100644
--- a/docs/en/erlang.mk/1/guide/installation.asciidoc
+++ b/docs/en/erlang.mk/1/guide/installation.asciidoc
@@ -28,6 +28,9 @@ Alpine Linux and other distributions based on BusyBox come
 with an incompatible `awk` program. Installing the GNU Awk
 (`gawk` on Alpine) solves this issue.
 
+Parallel builds may require the program `flock` that can
+be found in the package `util-linux`.
+
 ==== FreeBSD
 
 FreeBSD comes with binary and source packages:
@@ -56,6 +59,11 @@ is the one provided by Apple.
 [source,bash]
 $ sudo port install erlang git gmake
 
+Parallel builds may require the program `flock` which can
+be installed via Homebrew or manually. The instructions
+to install are available from its repository:
+https://github.com/discoteq/flock
+
 === On Windows
 
 Erlang.mk can be used on Windows inside an MSYS2 environment.
diff --git a/docs/en/erlang.mk/1/guide/installation/index.html b/docs/en/erlang.mk/1/guide/installation/index.html
index 3d49f35e..981bab8d 100644
--- a/docs/en/erlang.mk/1/guide/installation/index.html
+++ b/docs/en/erlang.mk/1/guide/installation/index.html
@@ -77,6 +77,7 @@ http://www.gnu.org/software/src-highlite -->
 <pre><tt>$ pacman -S erlang git make</tt></pre>
 </div></div>
 <p>Alpine Linux and other distributions based on BusyBox come with an incompatible <code>awk</code> program. Installing the GNU Awk (<code>gawk</code> on Alpine) solves this issue.</p>
+<p>Parallel builds may require the program <code>flock</code> that can be found in the package <code>util-linux</code>.</p>
 <h4 id="_freebsd">FreeBSD</h4>
 <p>FreeBSD comes with binary and source packages:</p>
 <div class="listingblock"><div class="title">Install binary packages</div>
@@ -104,6 +105,7 @@ http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
 <pre><tt>$ sudo port install erlang git gmake</tt></pre>
 </div></div>
+<p>Parallel builds may require the program <code>flock</code> which can be installed via Homebrew or manually. The instructions to install are available from its repository: <a href="https://github.com/discoteq/flock">https://github.com/discoteq/flock</a></p>
 <h2 id="_on_windows">On Windows</h2>
 <p>Erlang.mk can be used on Windows inside an MSYS2 environment. Cygwin, MSYS (the original) and native Windows (both Batch and PowerShell) are currently not supported.</p>
 <p>NOTE: Erlang.mk expects Unix line breaks in most of the files (LF instead of CRLF). Make sure to configure your text editor adequately.</p>
diff --git a/docs/en/erlang.mk/1/guide/releases.asciidoc b/docs/en/erlang.mk/1/guide/releases.asciidoc
index f1e20e6b..92968ff8 100644
--- a/docs/en/erlang.mk/1/guide/releases.asciidoc
+++ b/docs/en/erlang.mk/1/guide/releases.asciidoc
@@ -124,7 +124,7 @@ Your release was upgraded!
 There is a *workaround* to get the semver value which is
 generated by Relx based on VCS history.
 
-Create a file 'rel/version' with only one line inside:
+Create a file 'config/version' with only one line inside:
 
 [source,erlang]
 {{ release_version }}
@@ -133,7 +133,7 @@ Add/Update the `overlay` section of your `relx.config`:
 
 [source,erlang]
 {overlay, [
-    {template, "rel/version", "version"}
+    {template, "config/version", "version"}
 ]}.
 
 When you run `make rel` it creates the file '$(RELX_OUTPUT_DIR)/example/version'
diff --git a/docs/en/erlang.mk/1/guide/releases/index.html b/docs/en/erlang.mk/1/guide/releases/index.html
index 3224897f..86dc56f1 100644
--- a/docs/en/erlang.mk/1/guide/releases/index.html
+++ b/docs/en/erlang.mk/1/guide/releases/index.html
@@ -152,7 +152,7 @@ http://www.gnu.org/software/src-highlite -->
 <p>Your release was upgraded!</p>
 <h2 id="_getting_relx_semver_value">Getting Relx semver value</h2>
 <p>There is a <strong>workaround</strong> to get the semver value which is generated by Relx based on VCS history.</p>
-<p>Create a file <em>rel/version</em> with only one line inside:</p>
+<p>Create a file <em>config/version</em> with only one line inside:</p>
 <div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
 by Lorenzo Bettini
 http://www.lorenzobettini.it
@@ -165,7 +165,7 @@ by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
 <pre><tt>{<font color="#FF6600">overlay</font>, [
-    {<font color="#FF6600">template</font>, <font color="#FF0000">"rel/version"</font>, <font color="#FF0000">"version"</font>}
+    {<font color="#FF6600">template</font>, <font color="#FF0000">"config/version"</font>, <font color="#FF0000">"version"</font>}
 ]}<font color="#990000">.</font></tt></pre>
 </div></div>
 <p>When you run <code>make rel</code> it creates the file <em>$(RELX_OUTPUT_DIR)/example/version</em> which contains the version value generated by Relx.</p>