2. envsetup.sh脚本（Android10）

建议先阅读：

envsetup.sh分析(旧版本Android)

envsetup.sh分析二(旧版本Android)

新版本的envsetup.sh脚本

1. add_lunch_combo函数被废弃

所谓的lunch-combo指的是大家每次lunch时，打印出来的，可供选择的lunch选项。

旧版本的Android，使用此函数来添加lunch-combo

新版本的Android，执行此函数时会提醒add_lunch_combo is obsolete，告知此命令已经废弃。

并提醒开发者Use COMMON_LUNCH_CHOICES in your AndroidProducts.mk instead.

采用COMMON_LUNCH_CHOICES变量，在AndroidProducts.mk文件中声明lunch-combo

function add_lunch_combo()
{
    if [ -n "$ZSH_VERSION" ]; then
        echo -n "${funcfiletrace[1]}: "
    else
        echo -n "${BASH_SOURCE[1]}:${BASH_LINENO[0]}: "
    fi
    echo "add_lunch_combo is obsolete. Use COMMON_LUNCH_CHOICES in your AndroidProducts.mk instead."
}

2. print_lunch_menu函数

打印出全部的lunch-combo

具体是通过调用get_build_var函数来获得

function print_lunch_menu()
{
    local uname=$(uname)
    echo
    echo "You're building on" $uname
    echo
    echo "Lunch menu... pick a combo:"

    local i=1
    local choice
    for choice in $(TARGET_BUILD_APPS= get_build_var COMMON_LUNCH_CHOICES)
    do
        echo "     $i. $choice"
        i=$(($i+1))
    done

    echo
}

2. get_build_var函数

此函数通过调用build/soong/soong_ui.bash --dumpvar-mode $1来获取build variable编译变量

关于build/soong/soong_ui.bash的分析，见soong_ui.bash脚本

函数代码如下：

# Get the exact value of a build variable.
function get_build_var()
{
    if [ "$BUILD_VAR_CACHE_READY" = "true" ]
    then
        eval "echo \"\${var_cache_$1}\""
    return
    fi

    local T=$(gettop)
    if [ ! "$T" ]; then
        echo "Couldn't locate the top of the tree.  Try setting TOP." >&2
        return
    fi
    (\cd $T; build/soong/soong_ui.bash --dumpvar-mode $1)
}

2. _lunch函数

_lunch函数是lunch命令执行时的语法补全函数。

即，当执行lunch命令时，按下tab键一次，则执行_lunch函数一次

_lunch函数提供给我们可供选择的lunch选项（显示出匹配的lunch-combo）

源码如下：

unset COMMON_LUNCH_CHOICES_CACHE
# Tab completion for lunch.
function _lunch()
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"

    if [ -z "$COMMON_LUNCH_CHOICES_CACHE" ]; then
        COMMON_LUNCH_CHOICES_CACHE=$(TARGET_BUILD_APPS= get_build_var COMMON_LUNCH_CHOICES)
    fi

    COMPREPLY=( $(compgen -W "${COMMON_LUNCH_CHOICES_CACHE}" -- ${cur}) )
    return 0
}

可以看到这个函数和print_lunch_menu一样都是通过get_build_var函数来获取编译变量COMMON_LUNCH_CHOICES

2. lunch函数

源代码如下，分析见注释：

function lunch()
{
    # 定义局部变量`answer`来存放用户通过`lunch`命令传进来的参数（即`lunch-combo`，可以是字符串或数字）
    local answer

    if [ "$1" ] ; then
        answer=$1
    else # 如果用户没有没有传进来任何值，则打印出`lunch-combo`列表，提示用户输入
        print_lunch_menu
        echo -n "Which would you like? [aosp_arm-eng] "
        read answer
    fi

    # 定义局部变量`selection`，用来存放`lunch-combo`字符串
    local selection=

    if [ -z "$answer" ] # 如果`answer`为空，则把`selection`设置为默认的`aosp_arm-eng`
    then
        selection=aosp_arm-eng
    elif (echo -n $answer | grep -q -e "^[0-9][0-9]*$")
    then # 如果`answer`是数字，则把`selection`设置为对应的`lunch-combo`字符串
        local choices=($(TARGET_BUILD_APPS= get_build_var COMMON_LUNCH_CHOICES))
        if [ $answer -le ${#choices[@]} ]
        then
            # array in zsh starts from 1 instead of 0.
            if [ -n "$ZSH_VERSION" ]
            then
                selection=${choices[$(($answer))]}
            else
                selection=${choices[$(($answer-1))]}
            fi
        fi
    else # 如果`answer`是字符串，则把`selection`赋值为`answer`
        selection=$answer
    fi

    export TARGET_BUILD_APPS=

    local product variant_and_version variant version

    product=${selection%%-*} # Trim everything after first dash
    variant_and_version=${selection#*-} # Trim everything up to first dash
    if [ "$variant_and_version" != "$selection" ]; then
        variant=${variant_and_version%%-*}
        if [ "$variant" != "$variant_and_version" ]; then
            version=${variant_and_version#*-}
        fi
    fi

    if [ -z "$product" ]
    then
        echo
        echo "Invalid lunch combo: $selection"
        return 1
    fi

    TARGET_PRODUCT=$product \
    TARGET_BUILD_VARIANT=$variant \
    TARGET_PLATFORM_VERSION=$version \
    build_build_var_cache
    if [ $? -ne 0 ]
    then
        return 1
    fi

    export TARGET_PRODUCT=$(get_build_var TARGET_PRODUCT)
    export TARGET_BUILD_VARIANT=$(get_build_var TARGET_BUILD_VARIANT)
    if [ -n "$version" ]; then
      export TARGET_PLATFORM_VERSION=$(get_build_var TARGET_PLATFORM_VERSION)
    else
      unset TARGET_PLATFORM_VERSION
    fi
    export TARGET_BUILD_TYPE=release

    echo

    set_stuff_for_environment
    printconfig
    destroy_build_var_cache
}

3. addcompletions函数

4. make函数

5. m函数

6. mm函数

7. mmm函数

8. gettop函数

gettop函数通过查找TOPFILE即build/make/core/envsetup.mk文件，来判断当前目录是否为Android源码顶层目录

如果当前目录不是顶层目录，则循环cd往上一级目录走，直到找到为止（或者走到根目录，然后报错）。

代码如下：

function gettop
{
    local TOPFILE=build/make/core/envsetup.mk
    if [ -n "$TOP" -a -f "$TOP/$TOPFILE" ] ; then
        # The following circumlocution ensures we remove symlinks from TOP.
        (cd $TOP; PWD= /bin/pwd)
    else
        if [ -f $TOPFILE ] ; then
            # The following circumlocution (repeated below as well) ensures
            # that we record the true directory name and not one that is
            # faked up with symlink names.
            PWD= /bin/pwd
        else
            local HERE=$PWD
            local T=
            while [ \( ! \( -f $TOPFILE \) \) -a \( $PWD != "/" \) ]; do
                \cd ..
                T=`PWD= /bin/pwd -P`
            done
            \cd $HERE
            if [ -f "$T/$TOPFILE" ]; then
                echo $T
            fi
        fi
    fi
}

9. croot函数

跳转到Android源码顶层目录

通过gettop函数获得顶层目录路径

function croot()
{
    local T=$(gettop)
    if [ "$T" ]; then
        if [ "$1" ]; then
            \cd $(gettop)/$1
        else
            \cd $(gettop)
        fi
    else
        echo "Couldn't locate the top of the tree.  Try setting TOP."
    fi
}

10. xgrep类函数

这类函数，其实就是把find和grep命令封装了一下，加上了一些参数，搜索起来针对性更强、效率更高。

函数名和对应的功能，如下：

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.

这里以cgrep为例子

function cgrep()
{
    find . -name .repo -prune -o -name .git -prune -o -name out -prune -o -type f \( -name '*.c' -o -name '*.cc' -o -name '*.cpp' -o -name '*.h' -o -name '*.hpp' \) \
        -exec grep --color -n "[email protected]" {} +
}

find命令

• -name参数指定搜索的文件名(例：find -name "MyCProgram.c" \在根目录下查找MyCProgram.c文件)
• -iname参数指定搜索的文件名且忽略大小写(例：find -iname "MyCProgram.c" \)
• -a与
• -o或
• -not非!
• -prune就像一个判断语句,当发现-prune前面的表达式math时,执行到-prune之后就会输出一个结果1（类似于$?值为1）与-o配合就是如果满足前面的条件则不执行后面的参数
• -type指定搜索的文件类型(例：s指socket，d指目录，f指文件)
• \( \)括号内部的参数是对括号前面参数的补充（我理解为子参数）
• -exec指定查找结束后，要执行的命令。{}将会被当前文件名取代(例：find -iname "MyCProgram.c" -exec md5sum {} \找到该文件后，用md5sum命令计算该文件的MD5验证和)

grep命令

• --color带色彩显示搜索结果
• -n显示行号

"[email protected]"是从命令行传进来的位置参数（即用户在shell中输入的跟在cgrep后面的参数）

大家弄明白了这些参数，是不是就理解cgrep的逻辑了。

以此类推：

• ggrep就是搜索.gradle文件
• jgrep就是搜索.java文件
• resgrep就是搜索.xml文件
• mangrep就是搜索AndroidManifest.xml文件
• sepgrep就是搜索sepolicy目录下的文件
• rcgrep就是搜索.rc文件
• mgrep就是搜索makefile文件
• treegrep就是搜索c|h|cpp|hpp|S|java|xml文件

详细的代码分析，这里就不赘述了。

11.hmm函数

hmm函数或者是hmm命令，用来打印help信息。

逻辑很简单，分为两点：

1. cat命令打印help信息

2. 遍历envsetup.sh查找函数并打印出来

第一点没啥说的，第二点的逻辑如下：

for i in `cat $T/build/envsetup.sh | sed -n "/^[[:blank:]]*function /s/function \([a-z_]*\).*/\1/p" | sort | uniq`; do
  A="$A $i"
done

for循环中的逻辑很好理解A="$A $i"，循环中不停的把变量i的值追加在变量A后面。

for循环每次迭代，从cat $T/build/envsetup.sh | sed -n "/^[[:blank:]]*function /s/function \([a-z_]*\).*/\1/p" | sort | uniq中获取值

我们可以将这个长指令，通过管道分割为一个个子命令：

cat $T/build/envsetup.sh cat envsetup.sh脚本

sed -n "/^[[:blank:]]*function /s/function \([a-z_]*\).*/\1/p" 搜索envsetup.sh脚本中的包含^[[:blank:]]*function的行，并将其function后面的关键字（即函数名）提取出来

sort 对函数名进行排序

uniq 去除重复函数（uniq于检查及删除文本文件中重复出现的行列，一般与 sort 命令结合使用）

源码如下：

function hmm() {
cat <<EOF

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.
- 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.

Look at the source to view more functions. The complete list is:
EOF
    local T=$(gettop)
    local A=""
    local i
    for i in `cat $T/build/envsetup.sh | sed -n "/^[[:blank:]]*function /s/function \([a-z_]*\).*/\1/p" | sort | uniq`; do
      A="$A $i"
    done
    echo $A
}