Android source build/envsetup.sh 该知道的细节

1. 前言

        在编译Android源码时，开始一定会初始化系统环境变量，两条熟悉的命令：

        source build/envsetup.sh

        lunch  xxx

       那这样子初始化，有什么作用呢，初始化环境变量后有哪些快捷开发指令可以用呢? 我们来总结一下。

2.  envsetup.sh命令

        执行 source build/envsetup.sh命令时，这里的envsetup.sh被link到了 build/make/envsetup.sh文件

 此时在终端输入 hmm 命令，如下：

home@home-MS-7B89:~/project/code$ hmm
 
Run "m help" for help with the build system itself.
 
Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- lunch:      lunch <product_name>-<build_variant>
              Selects <product_name> as the product to build, and <build_variant> as the variant to
              build, and stores those selections in the environment to be read by subsequent
              invocations of 'm' etc.
- tapas:      tapas [<App1> <App2> ...] [arm|x86|mips|arm64|x86_64|mips64] [eng|userdebug|user]
- croot:      Changes directory to the top of the tree, or a subdirectory thereof.
- m:          Makes from the top of the tree.
- mm:         Builds all of the modules in the current directory, but not their dependencies.
- mmm:        Builds all of the modules in the supplied directories, but not their dependencies.
              To limit the modules being built use the syntax: mmm dir/:target1,target2.
- mma:        Builds all of the modules in the current directory, and their dependencies.
- mmma:       Builds all of the modules in the supplied directories, and their dependencies.
- umake:     Call ninja directly to speed up build when there is no modifications to .mk or .bp files.
- provision:  Flash device with all required partitions. Options will be passed on to fastboot.
- cgrep:      Greps on all local C/C++ files.
- ggrep:      Greps on all local Gradle files.
- jgrep:      Greps on all local Java files.
- resgrep:    Greps on all local res/ xml files.
- mangrep:    Greps on all local AndroidManifest.xml files.
- mgrep:      Greps on all local Makefiles files.
- sepgrep:    Greps on all local sepolicy files.
- sgrep:      Greps on all local source files.
- godir:      Go to the directory containing a file.
- allmod:     List all modules.
- gomod:      Go to the directory containing a module.
- pathmod:    Get the directory containing a module.
- refreshmod: Refresh list of modules for allmod/gomod.
 
Environment options:
- SANITIZE_HOST: Set to 'true' to use ASAN for all host modules. Note that
                 ASAN_OPTIONS=detect_leaks=0 will be set by default until the
                 build is leak-check clean.
- ANDROID_QUIET_BUILD: set to 'true' to display only the essential messages.

逐个解释说明一下：

2.1 croot 

        croot的中文翻译为“根”，大致意思就是回到工程代码的根目录，比如你在某个模块下面，想回到根目录，执行此命令：

home@home-MS-7B89:~/project/mount/cts/android11$ cd frameworks/base/packages/services/
home@home-MS-7B89:~/project/mount/cts/android11/frameworks/base/packages/services$ croot
home@home-MS-7B89:/mnt/mount/cts/android11$ 

2.2  gomod  <module>

        直接跳转到某个子模块，这个很方便切换查看模块代码

home@home-MS-7B89:/mnt/mount/cts/android11$ gomod Settings
home@home-MS-7B89:/mnt/mount/cts/android11/packages/apps/Settings$

2.3 pathmod <module>

        显示当前模块的路径 和 pwd 命令同样的意思

home@home-MS-7B89:/mnt/mount/cts/android11/packages/apps/Settings$ pathmod Settings
/mnt/mount/cts/android11/packages/apps/Settings

2.4  m  mm  mmm 

        编译整个工程，编译某个模块常用命令

对于m、mm、mmm、mma、mmma这些命令的实现都是通过make方式来完成的。

mmm/mm编译的效率很高，而make/mma/mmma编译较缓慢；

make/mma/mmma编译时会把所有的依赖模块一同编译，但mmm/mm不会;

建议：首次编译时采用make/mma/mmma编译；当依赖模块已经编译过的情况，则使用mmm/mm编译。

2.5  umake

        当修改某个模块的代码，没有新增加新java文件，资源文件，没有修改Android.bp Android.mk，用此命令可以加速编译速度。

2.6  grep 搜索

        这些命令可以非常快捷，高效查找到目标文件

        jgrep   "findString" :        在此目录下搜索包含findString 的所有java文件

       mgrep   "findString"  ：   在此目录下搜索包含findString 的所有mk文件

      resgrep  "findString" :       在此目录下搜索包含findString的所有资源(xml)文件

     mangrep  "findString" :      在此目录下搜索包含findString的所有AndroidManifest.xml 文件

3.  lunch命令

        当执行完lunch命令后：

============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=11
TARGET_PRODUCT=full_k79v1_64
TARGET_BUILD_VARIANT=userdebug
TARGET_BUILD_TYPE=release
TARGET_ARCH=arm64
TARGET_ARCH_VARIANT=armv8-a
TARGET_CPU_VARIANT=cortex-a53
TARGET_2ND_ARCH=arm
TARGET_2ND_ARCH_VARIANT=armv8-a
TARGET_2ND_CPU_VARIANT=cortex-a53
HOST_ARCH=x86_64
HOST_2ND_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-5.13.0-41-generic-x86_64-Ubuntu-20.04.3-LTS
HOST_CROSS_OS=windows
HOST_CROSS_ARCH=x86
HOST_CROSS_2ND_ARCH=x86_64
HOST_BUILD_TYPE=release
BUILD_ID=RP1A.200720.011
OUT_DIR=out
============================================

我们对这些参数进行解释说明：