轉載：http://home.lupaworld.com/home-space-uid-131820-do-blog-id-149462.html
build/envsetup.sh 腳本分析(lunch函數)
lunch函數提供了一個菜單，讓開發人員選擇需要編譯的目標產品(target product)和變體(variant)，並做一些檢查，設置環境變量，並打印出主要的環境變量。
直接運行lunch(必須先運行 build/envsetup.sh，讓lunch函數駐留到環境變量中)
ning@ning-desktop:~/donut-compare/mydroid$ lunch
You're building on Linux
generic-eng simulator aosp_emulator_us-eng aosp_emulator_eu-eng aosp_dream_us-userdebug aosp_dream_eu-userdebug aosp_dream_us-eng aosp_dream_eu-eng aosp_sapphire_us-userdebug aosp_sapphire_eu-userdebug aosp_sapphire_us-eng aosp_sapphire_eu-eng
Lunch menu... pick a combo:
1. generic-eng
2. simulator
3. aosp_emulator_us-eng
4. aosp_emulator_eu-eng
5. aosp_dream_us-userdebug
6. aosp_dream_eu-userdebug
7. aosp_dream_us-eng
8. aosp_dream_eu-eng
9. aosp_sapphire_us-userdebug
10. aosp_sapphire_eu-userdebug
11. aosp_sapphire_us-eng
12. aosp_sapphire_eu-eng
Which would you like? [generic-eng] 7
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=1.6
TARGET_PRODUCT=aosp_dream_us
TARGET_BUILD_VARIANT=eng
TARGET_SIMULATOR=false
TARGET_BUILD_TYPE=release
TARGET_ARCH=arm
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=Donut
============================================
用戶也可以直接輸入參數，不使用菜單
ning@ning-desktop:~/donut-compare/mydroid$ lunch aosp_dream_us-eng
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=1.6
TARGET_PRODUCT=aosp_dream_us
TARGET_BUILD_VARIANT=eng
TARGET_SIMULATOR=false
TARGET_BUILD_TYPE=release
TARGET_ARCH=arm
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=Donut
============================================
下面是lunch函數源代碼，用藍色添加了一下注釋，便於閱讀：
function lunch()
{
local answer
if [ "$1" ] ; then
# lunch後面直接帶參數
answer=$1
else
# lunch後面不帶參數，則打印處所有的target product和variant菜單提供用戶選擇
print_lunch_menu
echo -n "Which would you like? [generic-eng] "
read answer
fi
local selection=
if [ -z "$answer" ]
then
# 如果用戶在菜單中沒有選擇，直接回車，則爲系統缺省的generic-eng
selection=generic-eng
elif [ "$answer" = "simulator" ]
then
# 如果是模擬器
selection=simulator
elif (echo -n $answer | grep -q -e "^[0-9][0-9]*$")
then
# 如果answer是選擇菜單的數字，則獲取該數字對應的字符串
if [ $answer -le ${#LUNCH_MENU_CHOICES[@]} ]
then
selection=${LUNCH_MENU_CHOICES[$(($answer-$_arrayoffset))]}
fi
# 如果 answer字符串匹配 *-*模式(*的開頭不能爲-)
elif (echo -n $answer | grep -q -e "^[^\-][^\-]*-[^\-][^\-]*$")
then
selection=$answer
fi
if [ -z "$selection" ]
then
echo
echo "Invalid lunch combo: $answer"
return 1
fi
# special case the simulator
if [ "$selection" = "simulator" ]
then
# 模擬器模式
export TARGET_PRODUCT=sim
export TARGET_BUILD_VARIANT=eng
export TARGET_SIMULATOR=true
export TARGET_BUILD_TYPE=debug
else
# 將 product-variant模式種的product分離出來
local product=$(echo -n $selection | sed -e "s/-.*$//")
# 檢查之，調用關係 check_product()->get_build_var()->build/core/config.mk比較羅嗦，不展開了
check_product $product
if [ $? -ne 0 ]
then
echo
echo "** Don't have a product spec for: '$product'"
echo "** Do you have the right repo manifest?"
product=
fi
# 將 product-variant模式種的variant分離出來
local variant=$(echo -n $selection | sed -e "s/^[^\-]*-//")
# 檢查之，看看是否在 (user userdebug eng) 範圍內
check_variant $variant
if [ $? -ne 0 ]
then
echo
echo "** Invalid variant: '$variant'"
echo "** Must be one of ${VARIANT_CHOICES[@]}"
variant=
fi
if [ -z "$product" -o -z "$variant" ]
then
echo
return 1
fi
export TARGET_PRODUCT=$product
export TARGET_BUILD_VARIANT=$variant
export TARGET_SIMULATOR=false
export TARGET_BUILD_TYPE=release
fi # !simulator
echo
# 設置到環境變量，比較多，不再一一列出，最簡單的方法 set >env.txt 可獲得
set_stuff_for_environment
# 打印一些主要的變量, 調用關係 printconfig()->get_build_var()->build/core/config.mk->build/core/envsetup.mk 比較羅嗦，不展開了
printconfig
}