一. 首先在Android源代码目录下的build目录下，有个脚本文件envsetup.sh，执行这个脚本文件后，就可以获得一些有用的工具：
USER-NAME@MACHINE-NAME:~/Android$ . ./build/envsetup.sh
注意，这是一个source命令，执行之后，就会有一些额外的命令可以使用：
- croot: Changes directory to the top of the tree.
- m: Makes from the top of the tree.
- mm: Builds all of the modules in the current directory.
- mmm: Builds all of the modules in the supplied directories.
- cgrep: Greps on all local C/C++ files.
- jgrep: Greps on all local Java files.
- resgrep: Greps on all local res/*.xml files.
- godir: Go to the directory containing a file.
这些命令的具体用法，可以在命令的后面加-help来查看，这里我们只关注mmm命令，也就是可以用它来编译指定目录的所有模块，通常这个目录只包含一个模块。
二. 使用mmm命令来编译指定的模块，例如Email应用程序：
USER-NAME@MACHINE-NAME:~/Android$ mmm packages/apps/Email/
编译完成之后，就可以在out/target/product/generic/system/app目录下看到Email.apk文件了。Android系统自带的App都放在这具目录下。另外，Android系统的一些可执行文件，例如C编译的可执行文件，放在out/target/product/generic/system/bin目录下，动态链接库文件放在out/target/product/generic/system/lib目录下，out/target/product/generic/system/lib/hw目录存放的是硬件抽象层（HAL）接口文件，后面的文章里面，我们会陆续提及到，敬请关注。
出现
frameworks/av/camera/cameraserver/Android.mk:18: Target has integrated cameraserver into mediaserver. This is weakening security measures introduced in 7.0
find: ‘/home/xuanan/android/lineage/out/target/common/obj/SHARED_LIBRARIES/libwifi-hal-mock_intermediates’: No such file or directory
Starting build with ninja
ninja: Entering directory `.'
[ 0% 14/48263] Lex: aidl <= system/tools/aidl/aidl_language_l.ll
FAILED: /bin/bash -c "prebuilts/misc/linux-x86/flex/flex-2.5.39 -o/home/xuanan/android/lineage/out/host/linux-x86/obj/STATIC_LIBRARIES/libaidl-common_intermediates/aidl_language_l.cpp system/tools/aidl/aidl_language_l.ll"
flex-2.5.39: loadlocale.c:130: _nl_intern_locale_data: Assertion `cnt < (sizeof (_nl_value_type_LC_TIME) / sizeof (_nl_value_type_LC_TIME[0]))' failed.
Aborted (core dumped)
[ 0% 14/48263] target Java: libprotob...tobuf-java-nano_intermediates/classes)
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
[ 0% 14/48263] target Java: libphonen...number-platform_intermediates/classes)
ninja: build stopped: subcommand failed.
build/core/ninja.mk:151: recipe for target 'ninja_wrapper' failed
make: *** [ninja_wrapper] Error 1
make: Leaving directory '/home/xuanan/android/lineage'
解决方案：
This will do the trick:
export LC_ALL=C
Add it to yourbashrcfile or equivalent.
