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+.\" Copyright 2012 The Kyua Authors.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions are
+.\" met:
+.\"
+.\" * Redistributions of source code must retain the above copyright
+.\"   notice, this list of conditions and the following disclaimer.
+.\" * Redistributions in binary form must reproduce the above copyright
+.\"   notice, this list of conditions and the following disclaimer in the
+.\"   documentation and/or other materials provided with the distribution.
+.\" * Neither the name of Google Inc. nor the names of its contributors
+.\"   may be used to endorse or promote products derived from this software
+.\"   without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+.\" A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+.\" OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+.\" OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.Em Build directories
+(or object directories, target directories, product directories, etc.) is
+the concept that allows a developer to keep the source tree clean from
+build products by asking the build system to place such build products
+under a separate subtree.
+.Pp
+Most build systems today support build directories.
+For example, the GNU Automake/Autoconf build system exposes such concept when
+invoked as follows:
+.Bd -literal -offset indent
+$ cd my-project-1.0
+$ mkdir build
+$ cd build
+$ ../configure
+$ make
+.Ed
+.Pp
+Under such invocation, all the results of the build are left in the
+.Pa my-project-1.0/build/
+subdirectory while maintaining the contents of
+.Pa my-project-1.0/
+intact.
+.Pp
+Because build directories are an integral part of most build systems, and
+because they are a tool that developers use frequently,
+.Nm
+supports build directories too.
+This manifests in the form of
+.Nm
+being able to run tests from build directories while reading the (often
+immutable) test suite definition from the source tree.
+.Pp
+One important property of build directories is that they follow (or need to
+follow) the exact same layout as the source tree.
+For example, consider the following directory listings:
+.Bd -literal -offset indent
+src/Kyuafile
+src/bin/ls/
+src/bin/ls/Kyuafile
+src/bin/ls/ls.c
+src/bin/ls/ls_test.c
+src/sbin/su/
+src/sbin/su/Kyuafile
+src/sbin/su/su.c
+src/sbin/su/su_test.c
+
+obj/bin/ls/
+obj/bin/ls/ls*
+obj/bin/ls/ls_test*
+obj/sbin/su/
+obj/sbin/su/su*
+obj/sbin/su/su_test*
+.Ed
+.Pp
+Note how the directory layout within
+.Pa src/
+matches that of
+.Pa obj/ .
+The
+.Pa src/
+directory contains only source files and the definition of the test suite
+(the Kyuafiles), while the
+.Pa obj/
+directory contains only the binaries generated during a build.
+.Pp
+All commands that deal with the workspace support the
+.Fl -build-root Ar path
+option.
+When this option is provided, the directory specified by the
+option is considered to be the root of the build directory.
+For example, considering our previous fake tree layout, we could invoke
+.Nm
+as any of the following:
+.Bd -literal -offset indent
+$ kyua __COMMAND__ --kyuafile=src/Kyuafile --build-root=obj
+$ cd src && kyua __COMMAND__ --build-root=../obj
+.Ed